SECONDARY EDUCATION CERTIFICATEEXAMINATION

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The catalyst manganese(IV) oxide can be used to alter the rate of decomposition ofhydrogen peroxide.

Jonathan carried out an experiment at RTP (room temperature and pressure) to deter-mine the rate of decomposition of hydrogen peroxide using manganese(IV) oxide asthe catalyst. He did this by measuring the volume of oxygen given off at different timeintervals. Water is also produced during the decomposition and the reaction is exothermic.

Table 1 records Jonathan's results using manganese (IV) oxide and 100 cm3 of 0.80 moldm-3 hydrogen peroxide.

Karen carried out a similar experiment to Jonathan using 100 cm3 of 0.40 mol dm-3

hydrogen peroxide solution. Figure 1 on page 3 shows a graph of the data obtained byKaren.

Time (8) Volume ofOz at RTP (cm3)

1 015 430 845 12

60 16

75 19

90 21105 23120 23

.... ;-mm:rm'r_.•••.....+.. '_"" ,,,,,. _', ·

24 "" '" ...,... ...'r'T"!'rr', . , ' , ,j-"',

Ill-- __!'6 Ill_g·!~

i'2 _~o•...js_'_4-1_o ",,'.lrHili1ifl]U ..fill.

20 40 60 80Time (s)

IFF:.I •••I

1Ut'::""...

: ;

Figure 2 is a diagram of the enthalpy change for an exothermic reaction showing theeffect of a catalyst on the reaction pathway.

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(ii) Write a balanced equation to show the decomposition of hydrogen peroxide bymanganese(IV) oxide (MnOz).

(iii) Using the same axes as the graph (Figure 1) on page 3, plot a graph ofthe volumeof oxygen against time using the data in Table 1.

The first three points have been plotted for you on the graph. (3 marks)

(iv) Compare the plots obtained from Jonathan's and Karen's results in terms ofthe slope of the graph and the volume of oxygen produced. Account for thedifferences between Jonathan's and Karen's results.

b) the number of moles of oxygen produced in 45 seconds at RTP (roomtemperature and pressure).(1 mole of gas occupies 24 dm3 atRTP: Relative Atomic Mass 0 = 16)

(b) A student conducts a number of tests on an aqueous solution of Compound X. Someof the inferences and observations made are recorded in Table 2. Complete Table 2 byfilling in the missing observations and inferences.

Test Observation Inference

To 1 ml of a solution of X is added Brown gas evolves which turnsa few copper turnings, followed by moist blue litmus red.concentrated sulphuric acid.

(1 mark)

To 1 ml of a solution of X is addeddilute nitric acid followed by I- ions presentaqueous silver nitrate. Aqueousammonia is then added until inexcess. I- ions confirmed

(2 marks)

To 1 ml of a solution of X is added A bright yellow precipitateaqueous lead nitrate solution. forms.

Ionic equation required(2 marks)

(c) You are required to plan and design an experiment to compare the effects of thecatalysts manganese(IV) oxide and catalase on the rate of decomposition of hydrogenperoxide.

(i) Draw a CLEARLY labelled diagram of a suitable experimental arrangement forcarrying out the investigation in the laboratory. (2 marks)

The following statements were taken from a student's notebook. These statements areINCORRECT. In each case, you should state why the statement is incorrect and givethe correct statement.

(i) Sodium, magnesium, aluminium, silicon and chlorine are found in the samegroup in the periodic table.(Give your answer in terms of electron configuration.)

(ii) Of the elements magnesium and copper, magnesium will more readily oxidizean aqueous solution of zinc ions than copper will.

(b) P and Q both have an electron configuration of 2, 8, 1. The mass numbers of P and Qare 23 and 24 respectively.

(i) P reacts with water to produce a solution of its hydroxide and hydrogen gas.Write a balanced equation for the reaction between P and water.

(ii) Both P and Q give similar products when reacted with water. Account for thisobservation.

(2 marks)

GO ON TO THE NEXT PAGE

(iii) Q is radioactive. Radioactive substances are widely used in medicine, agricultureand industry. What is meant by the term 'radioactive'?

(c) Using dot-and-cross diagrams, show the bonding between Q and oxygen. [1~ 0]

3. But-I-ene (I-butene) and but-2-ene (2-butene) are structural isomers of molecular formulaC4HS"

(b) Ethanol reacts with different reagents to form products with the functional groups shownin Table 3.

Functional Group Reagents or Structure ofin Product Formed Reaction Conditions Organic Product Formed

"- /C=C

/ "-

Alkene (1 mark) (1 mark)

Ethanol

0 H 0II I II

-C - OH H-C -C - OHIH

Acid (1 mark)

0II

-C - OR

Ester (2 marks) (2 marks)

A pink solution of aqueous acidified potassium manganate(VII) is decolourisedby the addition of ferrous(Fe2+) ions. The chemical equation for the reaction is

Identify the oxidizing and reducing agents in the equation, and explain youranswer. (4 marks)

(ii) Iron(II) oxide reacts with dilute sulphuric acid to give a pale green solution.Write the equation for the reaction between iron(II) oxide and dilute sulphuricacid. (2 marks)

(iii) State whether the reaction in (ii) above is acid-base or redox, and explain youranswer. ( 3 marks)

What is meant by 'fermentation,' as it relates to the manufacture oflUm?(2 marks)

(iii) Suggest ONE material that could be used to produce wine by fermentation, andgive a reason for your suggestion. (2 marks)

5. The raw materials necessary for the extraction of iron from its ore are an iron ore, coke andlimestone.

(b) Outline the steps involved in the extraction of iron from its ore. Write a balanced chemicalequation for EACH step. (8 marks)

(c) Stainless steel, an alloy of iron, is used to make cooking utensils. Suggest TWO reasonswhy stainless steel is used instead of iron for making cooking utensils. ( 2 marks)

(e) Name the compound of iron that is found in the blood and explain how a lack of ironwould affect the human body. (3 marks)

Almost all animals eat their food raw, whereas humans tend to cook their food. Give TWOreasons why humans may need to cook their food. (2 marks)

Method 1 Place in a covered dish and bake.

Method 2 Chop into small pieces, add raw pineapple and boil.

Method 3 Chop into small pieces and boil in the pressure cooker.

(i) Select the method by which the lamb will take the LONGEST to cook.(1 mark)

(ii) Outline the principles involved in the functioning of the pressure cooker.(2 marks)

How does this differ from the use of the pressure cooker in Method 3?(4 marks)