PLACE LABEL HERE operating as an electrochemical cell, metallic zinc is plated from the electrolyte solution onto the negative electrode. Bromide ions are converted to bromine at the

Pages: 12 Questions: 7 ©Copyright for part(s) of this examination may be held by individuals and/or organisations other than the Tasmanian Qualifications Authority.

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Tasmanian Certificate of Education

CHEMISTRY

Senior Secondary

Subject Code: CHM315109

External Assessment

2012

Part 1

Time: approximately 45 minutes

On the basis of your performance in this examination, the examiners will provide a result on the following criterion taken from the course statement: Criterion 5 Demonstrate an understanding of the fundamental principles and

theories of electrochemistry. Criterion Mark

5 /40

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Chemistry – Part 1

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CANDIDATE INSTRUCTIONS Candidates MUST ensure that they have addressed ALL of the externally assessed criteria on this examination paper. Answer ALL questions (making sure you answer all parts within each question so that the criteria can be assessed). Answers must be written in the spaces provided on the examination paper. The 2012 Chemistry Information Sheet can be used throughout the examination. No other written material is allowed into the examination. A TQA approved calculator can be used throughout the examination. Each booklet is of equal value (40 marks). This examination is 3 hours in length; it is recommended that you spend no more than 45 minutes on any one of the FOUR parts to this examination. In calculations no credit can be given for incorrect answers unless they are accompanied by details of the working. Some credit will be given for unsimplified answers. Appropriate units must be included. All written responses must be in English.


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Question 1 (a) Calculate the oxidation state of manganese in each of the following compounds

containing manganese, and arrange the compounds in order of increasing oxidation state of the manganese.

KMnO4 , Na2MnO4 , MnCl2 , Mn CH3COO( )3 (2 marks) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. (b) Rank the compounds in order of decreasing oxidising ability. Explain your order. (2 marks) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. .............................................................................................................................................

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Question 2 Explain in what ways the reaction between magnesium and chlorine: Mg(s) +Cl2(g) !!!!!!!MgCl2(s) is similar to the reaction between magnesium and oxygen: 2Mg(s) +O2(g) !!!!!!!2MgO(s) How do the definitions of oxidation in terms of electron transfer and oxidation states relate to both reactions. (4 marks) ...................................................................................................................................................... ...................................................................................................................................................... ...................................................................................................................................................... ...................................................................................................................................................... ...................................................................................................................................................... ...................................................................................................................................................... ...................................................................................................................................................... ...................................................................................................................................................... ...................................................................................................................................................... ...................................................................................................................................................... ...................................................................................................................................................... ......................................................................................................................................................

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Question 3 Gold metal does not react with oxygen, water or dilute acids. It does react with a mixture of concentrated hydrochloric and nitric acids.

Au(s) + 3NO3! (aq)! + !4Cl–(aq) + 6H

+(aq) !!!!!!!AuCl4

!!"!(aq) !+ !3NO2(g) + 3H2O(!) Write the half equations that represent the oxidation and reduction processes. (4 marks) • oxidation half equation ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. • reduction half equation ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. • Hence show how they add to give the overall equation given above. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. • Comment on the role of the Cl– ions. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. .............................................................................................................................................

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Question 4 Standard electrode potentials for the Cu2+ and Cr3+ ions are: Cu2+!!!!(aq) + 2e

– Cu(s) : E˚ = 0.34 V

Cr3+!!!!(aq) + 3e– Cr(s) : E˚ = –0.74 V

(a) What do these two equations tell us about the relative reducing ability of the metals and

what is the significance of the different signs of the E˚ values? (3 marks) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. (b) Use chemical shorthand to represent the electrochemical cell formed from these two

half cells. Write the balanced overall equation for this cell and calculate the maximum cell EMF. (3 marks)

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Question 4 continues opposite.

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Question 4 (continued) (c) Which one of the following would you use for storage: • a copper container for chromium (III) chloride? • a chromium container for copper sulfate? Explain your choice. (3 marks) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. .............................................................................................................................................

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Question 5 The diagram below shows how an impure sample of copper can be electrolytically-refined. The impurities are zinc, gold and silver metals.

(a) On the diagram label, (i) the charges on the electrodes (ii) a suitable aqueous electrolyte (iii) the anode and the cathode (iv) the impure sample of copper and the electrode where pure copper is deposited. (2 marks)

(b) By considering the reactions that are possible at both electrodes, discuss what happens to

each of the four metals during this electrolysis process. (4 marks) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. .............................................................................................................................................

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Question 6 From the information below describing a new type of battery, you are to draw a diagram showing how it operates as an electrochemical cell.

The zinc-bromine flow battery has a solution of zinc bromide stored in two chambers. One chamber is used to store the electrolyte for the positive electrode reactions and the other for the negative. The two chambers are separated by a porous ion-exchange membrane. This keeps the bromine from reaching the positive electrode while allowing the necessary transfer of ions. When operating as an electrochemical cell, metallic zinc is plated from the electrolyte solution onto the negative electrode. Bromide ions are converted to bromine at the positive electrode and are immediately converted to a safe organic complex in the electrolyte.

Draw and label the diagram, including the following: • the anode and the cathode and the ions present in each cell • the electron flow in the external circuit and the movement of ions through the membrane • the anode and cathode reactions and the overall reaction. (5 marks)

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Question 7 (a) The Sydney Harbour Bridge is always being painted,

because by the time the painters have completed painting they need to start again.

Explain the chemistry behind why the painting is necessary and how the painting is

effective. (4 marks) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. (b) A sign on the bridge over the mouth of the Cam River at Somerset says: ‘cathodic

protection works in progress’. Outline the chemical principles involved in cathodic protection. (2 marks)

............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. (c) Explain why bridges near the sea need greater protection than those in a warm, dry inland

location. (2 marks) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. .............................................................................................................................................

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This question paper and any materials associated with this examination (including answer booklets, cover sheets, rough note paper, or information sheets) remain the property of the Tasmanian Qualifications Authority.


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CHEMISTRY

Senior Secondary


External Assessment

2012

Part 2


On the basis of your performance in this examination, the examiners will provide a result on the following criterion taken from the course statement: Criterion 6 Demonstrate knowledge and understanding of the principles and

theories of thermochemistry, kinetics and equilibrium.

Criterion Mark

6 /40

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Question 8 The chemical equation for the combustion of propane is:

C3H8(g) !!+!!5O2(g) !!!!!!!3CO2(g) !!+!!4H2O(g)

(a) Describe how energy is involved in the reaction and how this relates to the overall heat of reaction. (3 marks)

............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. (b) Some bond energies for bonds in gaseous molecules are listed below:

Bond type Bond energy (kJ mol!1 ) Bond type Bond energy (kJ mol!1 ) C–H 416 O=O 498 C–C 346 O–H 463 C–O 358 C=O 804

Use the bond energies in the table, and your knowledge of chemical structures, to

calculate !H (kJmol !1 ) for the combustion of propane. (3 marks) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. .............................................................................................................................................

Question 8 continues opposite.

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Question 8 (continued) Consider the four graphs below showing changes in energy (kJ mol!1 ) against reaction coordinate. (c) One of these graphs represents the combustion of propane. Identify this graph, giving

reasons for your choice. Label the relevant features of this graph. (4 marks) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. (d) Identify the graph that represents a process most likely to proceed spontaneously at

room temperature? Explain your choice. (2 marks) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. .............................................................................................................................................

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1. 2. 3. 4.

Reaction coordinate


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Question 9 Consider the two experiments below: • an aqueous solution of silver nitrate added to an aqueous solution of sodium chromate

in test tube 1:

2Ag+!!(aq) +CrO42!!!!!!!(aq) !!!"!!!Ag2CrO4(s)

(yellow) • crystals of silver nitrate added to crystals of sodium chromate in test tube 2. Describe what you would expect to observe in the test tubes, comparing the reaction rates at room temperature. Give reasons for the difference. What you would expect to happen if water was added to the second test tube? (4 marks) ...................................................................................................................................................... ...................................................................................................................................................... ...................................................................................................................................................... ...................................................................................................................................................... ...................................................................................................................................................... ...................................................................................................................................................... ...................................................................................................................................................... ...................................................................................................................................................... ...................................................................................................................................................... ......................................................................................................................................................

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Question 10 What effect does an increase of temperature have on the rate of a reaction? Explain your answer using the collision theory. Include a kinetic energy distribution curve in your answer. (4 marks) ...................................................................................................................................................... ...................................................................................................................................................... ...................................................................................................................................................... ...................................................................................................................................................... ...................................................................................................................................................... ...................................................................................................................................................... ...................................................................................................................................................... ......................................................................................................................................................

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Question 11 Zinc metal reacts with hydrochloric acid at room temperature, whereas copper metal does not. The reaction is represented by:

Zn(s) + 2HCl(aq) !!!!!!!ZnCl2(aq) +H2(g) Wrapping copper wire around a piece of zinc increases the rate of reaction due to the catalytic oxidation of the copper. (a) On the axes below, draw graphs to illustrate the rate of production of hydrogen gas

with and without copper wire. Label each graph. (2 marks) (b) How does a catalyst increase the rate of a reaction? (1 mark) ............................................................................................................................................. .............................................................................................................................................

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Volume of hydrogen

time


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Question 12 Consider the reaction:

CaCO3(s) CaO(s) +CO2(g) Equilibrium can be established for this reaction in a closed container at constant temperature. (a) Comment on the relationship at equilibrium between the forward and reverse reaction

rates, activation energies and !H values. (3 marks) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. (b) Why would industries that produce quicklime (calcium oxide, CaO) not use a closed

container? (2 marks) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. .............................................................................................................................................

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Question 13 A NO2(g) / N2O4(g) mixture is in a syringe at room temperature. As the piston is gradually pushed in, the red-brown colour of NO2 darkens at first and then becomes progressively lighter. It is always darker than it was originally. The equation for equilibrium is: N2O4(g) 2NO2(g) colourless red-brown (a) Explain the experimental results using Le Chatelier’s Principle. (3 marks)

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............................................................................................................................................. (b) For this reaction !H = 59kJ. Write an expression for the equilibrium constant. Explain (using Le Chatelier’s Principle) what will happen to the value of the

equilibrium constant when the temperature is increased. (3 marks)

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Question 14 The graph below shows the concentrations, over time as conditions change, of three gases A, B and C. These gases react according to the equation: A(g) +B(g) 3C(g) ; !H!!<!!0 (a) Identify the time intervals between t0 and t3 during which the system is at equilibrium. (1 mark) ............................................................................................................................................. ............................................................................................................................................. (b) What change in the conditions would have been responsible for the changes in the

concentrations: (2 marks) (i) at t1 ? ................................................................................................................................... (ii) at t3 ?

(c) Complete the graph up to time t5, indicating the final state of the system. (3 marks)

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Time

Con

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t0 t1 t2 t3 t4 t5


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CHEMISTRY

Senior Secondary


External Assessment

2012

Part 3


On the basis of your performance in this examination, the examiners will provide a result on the following criterion taken from the course statement: Criterion 7 Demonstrate knowledge and understanding of the properties and

reactions of organic and inorganic matter.

Criterion Mark

7 /40

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Question 15 (a) An element has an atomic number of 20. Write its name and electronic configuration. (1 mark) ........................................................................................................................................... ........................................................................................................................................... (b) Sketch a graph of the first four successive ionisation energies versus the number of

electrons removed from this element. Explain how this relates to the electronic structure of the atom. (4 marks)

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Energy

Number of electrons removed

1 2 3 4


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Question 16 The noble gases were discovered after Mendeleev drew up his periodic table. (a) Argon was discovered in 1894 and its relative atomic mass was determined to be 39.9.

Mendeleev thought it should be 38. Give a reason why he might have thought 39.9 was wrong. (1 mark)

........................................................................................................................................... ........................................................................................................................................... (b) Some scientists suggested that the noble gases be placed in front of group 1 (the alkali

metals) and called group 0. Why is this position inconsistent with the structure of the periodic table? (2 marks)

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Question 17 Consider the third period elements. (a) Explain why these elements change from metals to non-metals across the period.

Describe the variation in the acid-base character of their oxides across the period. (3 marks) ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... (b) An element, E, in the third period of the Periodic Table has the following properties:

silvery; shiny solid; good electrical conductor; malleable; ductile; melting point 650˚C; density 1.75g cm–3; burns readily in air with a bright white light to form both an oxide and a nitride; forms a chloride of formula ECl2 .

Identify the element and write a balanced equation for the formation of the nitride. (2 marks) ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ...........................................................................................................................................

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Question 18 (a) Aspirin has the structure shown below. (3 marks)

• Identify the functional groups present. ........................................................................................................................................... ........................................................................................................................................... • From the following list circle those compounds that may react with aspirin. calcium carbonate sodium metal acidified potassium permanganate sodium hydroxide ethanol (b) Consider the two compounds: dimethylpropane and 1-chlorodimethylpropane. Write the structural formula for each and compare the physical properties of the

compounds. (3 marks) Structural formulae: dimethylpropane 1-chlorodimethylpropane Comparison of physical properties: ................................................................................. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ...........................................................................................................................................

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COOH

O–COCH3


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Question 19 A hydrocarbon has the following properties. • When fully combusted in excess oxygen, equal volumes of carbon dioxide and water

vapour are produced under conditions of constant temperature and pressure. • It reacts immediately with bromine water. • It has a relative molecular mass of 42. (a) Determine the molecular formula of this hydrocarbon and draw its structural formula. (3 marks) ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... (b) A steel vessel containing only the hydrocarbon was subjected to high pressure, in the

presence of a suitable catalyst. A strong, flexible, solid was formed. Name the solid and write an equation showing how it was formed. (3 marks)

(c) Name and draw the isomer of the hydrocarbon that does not react immediately with

the bromine water. (1 mark) ........................................................................................................................................... ...........................................................................................................................................

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Question 20 Sodium propanoate is an antifungal agent in bread. Various organic compounds can be used to prepare sodium propanoate by reacting them separately with sodium hydroxide. Name two compounds containing different functional groups that could be used. Write the two equations using structural formulae. (7 marks) Compound 1: .................................................................................................................................................... Equation: .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... Compound 2: .................................................................................................................................................... Equation: .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... ....................................................................................................................................................

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Question 21 The branched chain bromoalkane A was treated as shown in the following flow diagram. Compound C could not be oxidised further. (7 marks) Explain what Compound C might be. .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... Draw structural formula for B. Write an equation for the reaction A! B . .................................................................................................................................................... .................................................................................................................................................... ....................................................................................................................................................

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A C5H11Br

B C5H11O

C C5H10O

Heat with aqueous NaOH

Heat with acidified KMnO4


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PLACE LABEL HERE


CHEMISTRY

Senior Secondary


External Assessment

2012

Part 4


On the basis of your performance in this examination, the examiners will provide a result on the following criterion taken from the course statement:

Criterion 8 Apply logical processes to solve quantitative chemical problems.

Criterion Mark

8 /40

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Question 22 At 100˚C, solid ammonium nitrite decomposes according to the equation:

NH4NO2(s)!!!!!!!N2(g) + 2H2O(g) 224 kJ was released per mole of ammonium nitrite decomposed. Calculate the quantity of heat released if 2.52 g of solid ammonium nitrite is decomposed at 100˚C. (2 marks) .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... Question 23 Air that has a volume of 500 mL, a pressure of 99.4 kPa and a temperature of 32˚C is cooled to –15˚C. Calculate the volume of air at this temperature if the pressure is increased to 205.9 kPa. (3 marks) .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... ....................................................................................................................................................

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Question 24 A solution of iron (II) sulfate can be oxidised using acidified potassium permanganate. The ionic equation is:

MnO4! (aq)! + !5Fe2+!! (aq) + 8H

+(aq) !!!!!!!Mn2+!!!!(aq) !+ !5Fe

3+!!!!(aq) + 4H2O(l)

(a) Calculate the mass of solid potassium permanganate required to oxidise 2.40 g of

iron (II) sulfate. (4 marks) ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... A solution of iron (II) sulfate can also be oxidised, this time using acidified potassium dichromate. The ionic equation is:

Cr2O7! !!(aq)2! + !6Fe2+!! (aq) +14H

+(aq) !!!!!!!2Cr3+!!!!(aq) !+ !6Fe

3+!!!!(aq) + 7H2O(l)

(b) In a titration, 26.7 mL of a 0.0565 mol L!1 solution of potassium dichromate was

required to reach the end point with 25.00 mL of a solution of iron (II) sulfate.

Calculate the concentration of the iron (II) sulfate solution. (3 marks) ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ...........................................................................................................................................

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Question 25 Consider the data for the following reactions. 2NH3(g) N2(g) + 3H2(g) !H = 92! kJ N2(g) + 2O2(g) 2NO2(g) !H = 68! kJ 2H2O(g) 2H2(g) +O2(g) !H = 484!kJ Predict the heat released or absorbed in the reaction below for the oxidation of ammonia. 4NH3(g) + 7O2(g) 4NO2(g) + 6H2O(g) (4 marks) .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... ....................................................................................................................................................

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Question 26 Hydrogen fluoride gas, HF, dissolves in water and reacts with water to form a slightly acidic solution according to the equation: HF(aq) +H2O(l) F!!!(aq) +H3O

+!!(aq)

When 2.94 L of gaseous HF at 25˚C and 101.3 kPa was dissolved in enough water to produce 1.00 L of aqueous solution, the pH of this aqueous solution was found to be 2.10 at 25˚C. Calculate the amount (in mol) of gaseous HF that was dissolved in the water and the equilibrium concentrations of H3O

+!!(aq),!F

!!!(aq) !and!HF(aq). Hence calculate the Ka value

for HF(aq) . (5 marks) .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... ....................................................................................................................................................

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Question 27 Two chemistry students performed an experiment to determine the molar heat of solution of hydrated sodium thiosulfate, Na2S2O3.5H2O. They dissolved 5.80 g of hydrated sodium thiosulfate in 50.0 mL of water in a calorimeter. The temperature of the water dropped from 23.8˚C to 18.6˚C. Calculate the molar heat of solution of hydrated sodium thiosulfate. Give your answer to an appropriate number of significant figures. (4 marks) .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... ....................................................................................................................................................

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Question 28 A current of 1.2 A is passed through 100.0 mL of a 0.500 mol L!1 zinc sulfate solution for exactly five minutes. Calculate the mass of zinc that would be deposited on the cathode and the concentration of the zinc ions remaining in solution. (6 marks) .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... ....................................................................................................................................................

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Question 29 The silver content of a silver alloy can be determined as follows.

Take shavings from the alloy and completely dissolve them in nitric acid to obtain an aqueous solution of silver nitrate. Add an aqueous solution of sodium chloride to the silver nitrate solution until all the silver is precipitated as silver chloride.

In an experiment, a mass of 1.56 g of silver alloy shavings gave a precipitate of 1.57 g. Determine the percentage, by mass, of silver in the alloy. (4 marks) .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... ....................................................................................................................................................

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Question 30 In a laboratory experiment, 200 mL of 0.100 mol L!1 aqueous solution of aluminium sulfate, Al2 SO4( )3(aq) , is added to 300 mL of a 0.100 mol L!1 aqueous solution of barium chloride,

BaCl2(aq). A white solid identified as barium sulfate precipitates. Write the equation for this reaction, determine which reagent is in excess and calculate the maximum mass of the barium sulfate that can form. (5 marks) .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... ....................................................................................................................................................

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CHEMISTRY (CHM315109)

2012 External Examination Information Sheet

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Chemical Data and Constants QUANTITY APPROXIMATE VALUE Standard atmospheric pressure 1.000 atm 101.3 kPa 760.0 mm Hg Absolute zero temperature (zero kelvin) −273˚C Standard temperature & pressure (S.T.P.) 0˚C (273 K) and 101.3 kPa Standard laboratory conditions (S.L.C.) 25˚C (298 K) and 101.3 kPa Avogadro's constant (NA) 6.022 x 1023 mol−1

Ideal gas constant (R) 0.0821 L atm K−1 mol−1 8.31 J K−1 mol−1 8.31 L kPa K−1 mol−1

62.4 L mm Hg K−1 mol−1

Molar volume of an ideal gas (S.T.P.) 22.4 L mol−1

Molar volume of an ideal gas (S.L.C.) 24.5 L mol−1

Charge on the electron −1.602 x 10−19 C Faraday’s constant (F) 96 500 C mol−1

Specific heat of water (cw) 4.184 J g−1 K−1

Density of liquid water 1.00 g mL−1

One litre (1.00 L) 1000 mL or 1000 cm3

One cubic metre (1.00 m3) 1000 L Unit prefixes: nano (n) micro (µ) milli (m) kilo (k) mega (M) giga (G) tera (T) 10−9 10−6 10−3 103 106 109 1012

Page 2 of 10

Chemical Information n = m

M n = amount of substance (mol)

m = mass (g)

M = molar mass (g mol−1)

N = n NA N = number of particles

NA = Avogadro's constant (see p.1)

n = cV c = concentration (mol L−1)

V = volume of solution (L)

P1V1T1

=P2V2T2

Combined Gas Equation (n constant)

V = gas volume

P = gas pressure

PV = nRT T = temperature (K)

R = Ideal Gas Constant (see p.1)

n(e−) = amount of electrons (mol)

n(e! ) = qF=ItF

q = electrical charge (C)

F = Faraday Constant (see p.1)

E = energy change (J)

E = VIt V = potential difference (V)

I = electrical current (A)

t = time (s)

E =mc!T c = specific heat capacity (J g−1 K−1)

cf =E!T

=VIt!T

!T = temperature change (K)

cf = calibration factor (J K−1)

! =mV

! = density (g mL−1 or g L−1)

Page 3 of 10

COMMON POSITIVE IONS (CATIONS) 1+ 2+ 3+ 4+

ammonium NH4+ barium Ba2+ aluminium Al3+ tin (IV) Sn4+

hydrogen H+ calcium Ca2+ chromium (III) Cr3+ lead (IV) Pb4+ lithium Li+ copper (II) Cu2+ iron (III) Fe3+ potassium K+ iron (II) Fe2+ silver Ag+ lead (II) Pb2+ sodium Na+ mercury (II) Hg2+ magnesium Mg2+ nickel (II) Ni2+ tin (II) Sn2+ zinc Zn2+

COMMON NEGATIVE IONS (ANIONS) 1– 2– 3–

ethanoate (acetate) CH3COO– carbonate CO3

2– nitride N3– bromide Br– chromate CrO4

2– dichromate Cr2O7

2– phosphate PO4

3–

chloride Cl– hydrogen phosphate HPO42– phosphide P3–

dihydrogen phosphate H2PO4– oxide O2–

fluoride F– sulfate SO42–

hydrogen carbonate HCO3– sulfide S2–

hydrogen sulfate HSO4– sulfite SO3

2– hydrogen sulfide HS– thiosulfate S2O3

2– hydrogen sulfite HSO3

– oxalate C2O42–

hydroxide OH– iodide I– nitrate NO3

– nitrite NO2

– permanganate MnO4

– hydride H–

SOLUBILITY TABLE FOR COMMON IONIC COMPOUNDS Negative Ions (anions) Solubility of Compounds

ethanoates (acetates) (CH3COO– ) All soluble

nitrates (NO3– ) All soluble

chlorides (Cl– ) All soluble except AgCl, PbCl2, HgCl2 bromides (Br– ) All soluble except AgBr, PbBr2, HgBr

2

iodides (I– ) All soluble except AgI, PbI2, HgI2

sulfates (SO42– ) All soluble except BaSO

4, CaSO4, SrSO4, PbSO4, Ag2SO4, SnSO4

hydroxides (OH– ) All insoluble except LiOH, NaOH, KOH, RbOH, NH4OH,Sr(OH)2, Ba(OH)

2

sulfides (S2– ) All insoluble except Li2S, Na2S, K2S, Rb2S, (NH4 )2S, MgS, CaS, SrS, BaS

carbonates (CO32– ) All insoluble except Li2CO3, Na2CO3, K2CO3, Rb2CO3, (NH4 )2CO3

phosphates (PO43– ) All insoluble except Li3PO4, Na3PO4, K3PO4, Rb3PO4, (NH4 )3PO4

sulfites (SO32– ) All insoluble except Li2SO3, Na2SO3, K2SO3, Rb2SO3(NH4 )2SO3

Page 4 of 10

Chemical Equilibrium Formulae For the equilibrium system: xP + yQ zR + wS (where none of components P, Q, R or S is a solid)

Kc =R[ ]z S[ ]w

P[ ]x Q[ ]y

Kw = H+(aq)

!" #$ OH–(aq)

!" #$=1.00%10–14 mol2 L–2 at 25˚C

pH = –log H+(aq)

!" #$ NOTE: H+(aq)

!" #$= H3O+(aq)

!" #$

H+(aq)

!" #$=10%pH

Common Coloured Aqueous Ions

COLOURED CATIONS COLOURED ANIONS

chromium (III) Cr3+ green chromate CrO42− yellow

cobalt (II) Co2+ pink dichromate Cr2O72− orange

copper (II) Cu2+ blue permanganate MnO4− purple

iron (II) Fe2+ pale green iron (III) Fe3+ orange/brown (*most other non listed aqueous ions manganese (II) Mn2+ pale pink are colourless in solution) nickel (II) Ni2+ green Organic Chemistry Alkanes: CnH2n+2 Benzene C6H6 Alkenes: CnH2n Alkynes: CnH2n!2 Cyclic Alkanes: CnH2n Cyclic Alkenes: CnH2n!2

Stem Names

Carbon Atoms in Chain 1 2 3 4 5 6 7 8 9 10

Stem Name meth- eth- prop- but- pent- hex- hept- oct- non- dec-

Side chains and substitutes

methyl –CH3 bromo –Br ethyl –C2H5 chloro –Cl propyl –C3H7 fluoro –F iodo –I

Prefixes

Atoms in molecule 1 2 3 4 5 6 7 8 9 10

Prefix mono- di- tri- tetra- penta- hexa- hepta- octa- nona- deca-

CH CH

CH

CH

CH CH

Page 5 of 10

Functional Groups class of

compound functional group general formula example of

compound

alcohols

CnH2n+2O

propan-1-ol

aldehydes

CnH2nO

ethanal

carboxylic acids

CnH2nO2

butanoic acid

ketones

CnH2nO

pentan-3-one

esters

CnH2nO2

methyl propanoate

alkyl halides

CnH2n+1X

1-chlorobutane

OH

F Cl Br l

C

O

H

H

C

O

O

C

O

O

H C

H

C C O

H H H

H H H

H C

O

C

H H

H

H C

H

C C

H H H

H H H

O

C

O

H C Cl C C

H H H

H H H

C

H

H

H C H C

H H

H

C

O H

O

C

H

H

H H

H

C H

C H H

C C

C

H H

H

H

O

C O

Page 6 of 10

Some Organic Reactions of Aliphatic Compounds

Alcohol

Aldehyde RCHO

Carboxylic acid RCOOH

[O] using mild oxidiser eg acidified

dichromate

[O]

Ester RCOOR'

Conc H2SO4

Primary RCH2OH

Secondary RCHOHR'

Ketone RCOR'

Alkene

Loss of H2O (use H2SO4(l))

Dilute. NaOH (aq)

Alkane

H2

HX(g)

Polymer

[O]

[O] with excess stronger oxidiser

eg acidified permanganate

+H2O(g)

Carboxylic acid + alcohol RCOOH + R'OH

Hydrolysis (in presence of catalyst)

Salt (eg RCOONa) + H2O Salt (eg RCOONa) + H2 Salt (eg RCOONa) + H2O + CO2

base eg NaOH or active metal or carbonate

Alkoxide (RCH2O–) + ½H2

Active metal(eg Na)

Alkyl halide RX (X is F, Cl, Br or I).

Addition polymerisation (Catalyst)

Page 7 of 10

STANDARD REDUCTION POTENTIALS AQUEOUS IONS (1 mol/L and 25˚C)

REDUCTION HALF EQUATIONS

VERY STRONG

OXIDISERS

VERY WEAK

REDUCERS

E˚(volts)

F2(g) + 2e– 2F–(aq) +2.87 H2O2(aq) + 2H+(aq) + 2e– 2H2O(l) +1.78

Au3+(aq) + 3e– Au(s) +1.50 MnO4

–(aq) + 8H+(aq) + 5e– Mn2+(aq) + 4H2O(l) +1.49 Cl2(g) + 2e– 2Cl–(aq) +1.36 Cr2O7

2-(aq) + 14H+(aq) + 6e– 2Cr3+(aq) + 7H2O(l) +1.36 MnO2(s) + 4H+(aq) + 2e– Mn2+(aq) + 2H2O(l) +1.28 O2(g) + 4H+(aq) + 4e– 2H2O(l) +1.23 Br2(l) + 2e– 2Br–(aq) +1.09 NO3

–(aq) + 4H+(aq) + 3e– NO(g) + 2H2O(l) +0.96 Ag+(aq) + e– Ag(s) +0.80 Hg2+(aq) + 2e– Hg(l) +0.78 NO3

–(aq) + 2H+(aq) + e– NO2(g) + H2O(l) +0.78 Fe3+(aq) + e– Fe2+(aq) +0.77 O2(g) + 2H+(aq) + 2e– H2O2(aq) +0.68 I2(s) + 2e– 2I–(aq) INCREASING

STRENGTH AS

REDUCERS

+0.54 O2(g) + 2H2O(l) + 4e– 4OH–(aq) +0.40

Cu2+(aq) + 2e– Cu(s) +0.34 INCREASING STRENGTH

AS OXIDISERS

SO42-(aq) + 4H+(aq) + 2e– SO2(g) + 2H2O(l) +0.17

Sn4+(aq) + 2e– Sn2+(aq) +0.15 S(s) + 2H+(aq) + 2e– H2S(g) +0.14

2H+(aq) + 2e– H2(g) 0.00 Pb2+(aq) + 2e– Pb(s) –0.13 Sn2+(aq) + 2e– Sn(s) –0.14 Ni2+(aq) + 2e– Ni(s) –0.25 Co2+(aq) + 2e– Co(s) –0.28 Cd2+(aq) + 2e– Cd(s) –0.40 Fe2+(aq) + 2e– Fe(s) –0.41 Cr3+(aq) + 3e– Cr(s) –0.74 Zn2+(aq) + 2e– Zn(s) –0.76 2H2O(l) + 2e– 2OH–(aq) + H2(g) –0.83 Mn2+(aq) + 2e– Mn(s) –1.18 Al3+(aq) + 3e– Al(s) –1.71 Mg2+(aq) + 2e– Mg(s) –2.38 Na+(aq) + e– Na(s) –2.71 Ca2+(aq) + 2e– Ca(s) –2.87

VERY WEAK

OXIDISERS

Sr2+(aq) + 2e– Sr(s) VERY

STRONG

–2.89 K+(aq) + e– K(s) –2.92 Li+(aq) + e– Li(s) REDUCERS –3.05

OXIDATION HALF EQUATIONS

Page 8 of 10

TABLE OF RELATIVE ATOMIC MASSES (BASED ON 12C =12.00 )

Name

Symbol Atomic Number

Relative Atomic Mass

Name

Symbol Atomic

Number Relative Atomic Mass

actinium Ac 89 227.03 mercury Hg 80 200.6 aluminium Al 13 26.98 molybdenum Mo 42 95.94 americium Am 95 - neodymium Nd 60 144.2 antimony Sb 51 121.8 neon Ne 10 20.18 argon Ar 18 39.95 neptunium Np 93 - arsenic As 33 74.92 nickel Ni 28 58.71 astatine At 85 - niobium Nb 41 92.91 barium Ba 56 137.3 nitrogen N 7 14.01 berkelium Bk 97 - nobelium No 102 - beryllium Be 4 9.012 osmium Os 76 190.2 bismuth Bi 83 209.0 oxygen O 8 16.00 boron B 5 10.81 palladium Pd 46 106.4 bromine Br 35 79.90 phosphorus P 15 30.97 cadmium Cd 48 112.4 platinum Pt 78 195.1 caesium Cs 55 132.9 plutonium Pu 94 - calcium Ca 20 40.08 polonium Po 84 - californium Cf 98 - potassium K 19 39.10 carbon C 6 12.01 praseodymium Pr 59 140.9 cerium Ce 58 140.1 promethium Pm 61 - chlorine Cl 17 35.45 protactinium Pa 91 - chromium Cr 24 52.00 radium Ra 88 226.03 cobalt Co 27 58.93 radon Rn 86 - copper Cu 29 63.54 rhenium Re 75 186.2 curium Cm 96 - rhodium Rh 45 102.9 dysprosium Dy 66 162.5 rubidium Rb 37 85.47 einsteinium Es 99 - ruthenium Ru 44 101.1 erbium Er 68 167.3 samarium Sm 62 150.4 europium Eu 63 152.0 scandium Sc 21 44.96 fermium Fm 100 - selenium Se 34 78.96 fluorine F 9 19.00 silicon Si 14 28.09 francium Fr 87 - silver Ag 47 107.9 gadolinium Gd 64 157.3 sodium Na 11 22.99 gallium Ga 31 69.72 strontium Sr 38 87.62 germanium Ge 32 72.59 sulfur S 16 32.06 gold Au 79 197.0 tantalum Ta 73 180.9 hafnium Hf 72 178.5 technetium Tc 43 - helium He 2 4.002 tellurium Te 52 127.6 holmium Ho 67 164.9 terbium Tb 65 158.9 hydrogen H 1 1.008 thallium Tl 81 204.4 indium In 49 114.8 thorium Th 90 232.0 iodine I 53 126.9 thulium Tm 69 168.9 iridium Ir 77 192.2 tin Sn 50 118.7 iron Fe 26 55.85 titanium Ti 22 47.90 krypton Kr 36 83.80 tungsten W 74 183.9 lanthanum La 57 138.9 uranium U 92 238.0 lawrencium Lr 103 - vanadium V 23 50.94 lead Pb 82 207.2 xenon Xe 54 131.3 lithium Li 3 6.941 ytterbium Yb 70 173.0 lutetium Lu 71 175.0 yttrium Y 39 88.91 magnesium Mg 12 24.31 zinc Zn 30 65.37 manganese Mn 25 54.94 zirconium Zr 40 91.22 mendelevium Md 101 -

General Periodic Trends

1 H

2 He

3 Li

4 Be 5

B 6 C

7 N

8 O

9 F

10 Ne

11 Na

12 Mg 13

Al 14 Si

15 P

16 S

17 Cl

18 Ar

19 K

20 Ca

21 Sc

22 Ti

23 V

24 Cr

25 Mn

26 Fe

27 Co

28 Ni

29 Cu

30 Zn

31 Ga

32 Ge

33 As

34 Se

35 Br

36 Kr

37 Rb

38 Sr

39 Y

40 Zr

41 Nb

42 Mo

43 Tc

44 Ru

45 Rh

46 Pd

47 Ag

48 Cd

49 In

50 Sn

51 Sb

52 Te

53 I

54 Xe

55 Cs

56 Ba

57 La

72 Hf

73 Ta

74 W

75 Re

76 Os

77 Ir

78 Pt

79 Au

80 Hg

81 Tl

82 Pb

83 Bi

84 Po

85 At

86 Rn

87 Fr

88 Ra

Atomic radii decreases

Nuclear charge increases

Cation size decreases Anion size decreases

Shielding is constant

Ionisation energy increases

Ato

mic

radi

i inc

reas

es

Nuc

lear

cha

rge

incr

ease

s

Ioni

c si

ze in

crea

ses

Ionisation energy decreases

Shielding increases

Electronegativity increases

Electronegativity decreases

PERIODIC TABLE OF ELEMENTS

I II III IV V VI VII VIII

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 1 H Hydrogen 1.008

2 He Helium 4.002

3 Li Lithium 6.941

4 Be Beryllium 9.012

5 B Boron 10.81

6 C Carbon 12.01

7 N Nitrogen 14.01

8 O Oxygen 16.00

9 F Fluorine 19.00

10 Ne Neon 20.18

11 Na Sodium 22.99

12 Mg Magnesium 24.31

13 Al Aluminium 26.98

14 Si Silicon 28.09

15 P Phosphorus 30.97

16 S Sulfur 32.06

17 Cl Chlorine 35.45

18 Ar Argon 39.95

19 K Potassium 39.10

20 Ca Calcium 40.08

21 Sc Scandium 44.96

22 Ti Titanium 47.90

23 V Vanadium 50.94

24 Cr Chromium 52.00

25 Mn Manganese 54.94

26 Fe Iron 55.85

27 Co Cobalt 58.93

28 Ni Nickel 58.71

29 Cu Copper 63.54

30 Zn Zinc 65.37

31 Ga Gallium 69.72

32 Ge Germanium 72.59

33 As Arsenic 74.92

34 Se Selenium 78.96

35 Br Bromine 79.90

36 Kr Krypton 83.80

37 Rb Rubidium 85.47

38 Sr Strontium 87.62

39 Y Yttrium 88.91

40 Zr Zirconium 91.22

41 Nb Niobium 92.91

42 Mo Molybdenum 95.94

43 Tc Technetium

44 Ru Ruthenium 101.1

45 Rh Rhodium 102.9

46 Pd Palladium 106.4

47 Ag Silver 107.9

48 Cd Cadmium 112.4

49 In Indium 114.8

50 Sn Tin 118.7

51 Sb Antimony 121.8

52 Te Tellurium 127.6

53 I Iodine 126.9

54 Xe Xenon 131.3

55 Cs Caesium 132.9

56 Ba Barium 137.3

57 La Lanthanum 138.9

72 Hf Hafnium 178.5

73 Ta Tantalum 180.9

74 W Tungsten 183.9

75 Re Rhenium 186.2

76 Os Osmium 190.2

77 Ir Iridium 192.2

78 Pt Platinum 195.1

79 Au Gold 197.0

80 Hg Mercury 200.6

81 Tl Thallium 204.4

82 Pb Lead 207.2

83 Bi Bismuth 209.0

84 Po Polonium

85 At Astatine

86 Rn Radon

87 Fr Francium

88 Ra Radium

89 Ac Actinium

104 Rf

105 Db

106 Sg

107 Bh

108 Hs

109 Mt

110 Uun

111 Uun

112 Uub

113 114 115 116 117 118

58–71 Lanthanide Series 58 Ce Cerium 140.1

59 Pr Praseodymium 140.9

60 Nd Neodymium 144.2

61 Pm Promethium

62 Sm Samarium 150.4

63 Eu Europium 152.0

64 Gd Gadolinium 157.3

65 Tb Terbium 158.9

66 Dy Dysprosium 162.5

67 Ho Holmium 164.9

68 Er Erbium 167.3

69 Tm Thulium 168.9

70 Yb Ytterbium 173.0

71 Lu Lutetium 175.0

90–103 Actinide Series 90 Th Thorium 232.0

91 Pa Protactinium

92 U Uranium 238.0

93 Np Neptunium

94 Pu Plutonium

95 Am Americium

96 Cm Curium

97 Bk Berkelium

98 Cf Californium

99 Es Einsteinium

100 Fm Fermium

101 Md Mendelevium

102 No Nobelium

103 Lr Lawrencium

5 B Boron 10.81

Atomic number

Name

Relative atomic mass

Symbol

Documents

PLACE LABEL HERE operating as an electrochemical cell, metallic zinc is plated from the electrolyte solution onto the negative electrode. Bromide ions are converted to bromine at the