checklist for scoring A+ in chemistry

CHECKLIST FOR SCORING ‘A+’ IN CHEMISTRY SPM 2013

QUESTION ANSWER1.State the kinetic theory of matterState one example to support the kinetic theory of matter

-Matter consist of molecules. These are the smallest particles, which are capable of free existence and retain all the chemical properties of the parent substance.-The molecules are always in a state of random continuous motion.-The molecules exert forces on one another. These forces depend upon intermolecular distance.Gas.

2.What are atom,molecule,and ion Atom-smallest particle that can participate in chemical reactionMolecule-Group of 2 or more atoms which are chemically bonded togetherIon-Charged particle

3.What is melting point? Melting Point-The temperature that remains constant at which a solid changes into a liquid at aparicular pressure

4.Define proton number and nucleon number Proton Number-The number of proton presence in an atomNucleon Number-The total number of proton and neutron in an atom

5.State the meaning of isotopes -Atoms of the same element with the same number of proton but different number of neutrons

6.State the uses of isotopes such as carbon-14 and cobalt-60

Cobalt-60:Radiotheraphy of treating cancerCarbon-14:Carbon dating(estimate age of fossils and artefacts)

7.Explain why the temperature remains unchanged during the melting process

-This is because the heat energy absorbed by the particles is used to overcome the forces of attraction between the particles

8.Explain why the temperature remains unchanged during the freezing point

-This is because the heat loss to the surrounding is balanced to the heat energy liberatedas the particle attracts one another to form solid

9.A solid compound is heated until it converts into gas.Explain the changes in energy content,forces of attraction between the particles and arrangement of particles

-When a solid is heated,the particles in the solid absorb heat energy and vibrate stronger at its fixed position due to the increase in kinetic energy of the particles .When the particles managed to overcome the strong force of attraction between them they will finally changed into liquid.In liquid form,the particles have a higher amount of kinetic energy than it is in solid and they can move in a more random manner.When it reaches the boiling


point,the particles can move freely and in a random manner as it has changed its state into gas which has the highest kinetic energy and the weakest force of attraction between particles

SOLID LIQUID GAS-Low Kinetic Energy

-Kinetic Energy is lower than it is in solid and higher than gas

-Low kinetic Energy

-High Force of Attraction Between Particles

-Force of attraction between paricles are as strong as it is in solid

-Low Force of attraction between particles

-Particles are Arranged in orderly manner-Rotate and vibrate at fixed position only

-Particles are closely packed together but can move in a random manner

-Particles can move freely and randomly

10.State the main subatomic particles of an atom.Compare and contrast the relative atomic mass and the relative charge of the subatomic particles of the atom

Subatomic Particles

Relative Atomic Mass

Relative Charge

Proton 1 +1Neutron 1 0Electron 0.0005 -1

11. Al1327 is the symbol of aluminium

a)Determine the number of neutron of aluminiumb)Draw the electron arrangement of aluminium

a)Neutron number=14b)


12.Solid Z has a melting point of 65C.Describe a laboratory experiment to determine the melting point of Z.Your answer should show how the melting point of Z is determined

1.A boiling tube is filled with solid Z to a depth of 3cm and thermometer is put into it2.The boiling tube is suspended in a beaker half filled with water using a retort stand and clamp.The level of solid Z in the boiling tube must be below the level of water in the beaker.3.The water is heated and the solid Z is stirred slowly with the thermometer.When the temperature of the solid Z reaches 450C,the stopwatch is started.4.The temperature and the state of substance Z is recorded at half minute intervals until the temperature of substance Z reaches 800C.

13.Compound W has a freezing point of 82C.Describe a laboratory experiment to determine the freezing point of W

1.Step 1 to 2 of the above experiment is repeated using compound W instead.2.The water is heated and the compound W is stirred slowly with the thermometer.When compound W reaches 950C,the heating is stopped3.The boiling tube is removed from the water bath and the outer surface is dried up.Then it is immediately put into a conical flask with half of the top of the boiling tube clamped using a retort stand.The compound W is stirred continuosly.4.The temperature and the state of compound W is recorded at half-minute intervals until the temperature drops to about 750C.


QUESTION ANSWER1.State the meaning of relative atomic mass based in carbon-12 scale

-Number of times the mass of an atom is greater than a/12 times of the mass of a carbon-12 atom. The relative mass of carbon-12 atom is 12.000.

2. Define a mole -An amount of substance that contains as many particles as the number of atom in exaclt 12g of carbon-12

3.State the meaning of molar mass -Mass of 1mol of substance of units,molecules or atoms.

4.State the meaning of molar volume of gas -The volume occupied by one mole of gas.5.State the meaning of empirical formula -The formula that shows the simplest whole

number ratio of atoms of each element in the compound.

6.State the meaning of molecular formula -The formula that shows the actual number of atoms of each element that is present in a molecule of the compound-Molecular formula=(empirical formula)n

7.Explain why we couldn’t determine the empirical formula of copper()oxide by heating copper powder in a crucible

-This is because copper is not a reactive metal so it will take a long time for It to react with the oxygen in air.Thus,to determine the empirical formula of copper()oxide,another method is used.The method uses continuous flowing hydrogen gas to obtain copper metal from the reduction of copper()oxide.

8.Compare and contrast empirical formula with molecular formula using ethane as an example Ethane

Empirical Formula Molecular FormulaCH3 C2H6

9.Vinegar is a dilute ethanoic acid with a molecular formula CH3COOH.a)Find the empirical formula of ethanoic acidb)Find the percentage composition by mass of carbon in ethanoic acid

a)Empirical Formula:CH2Ob)Percentage of carbon in ethanoic acid=2(12) 100%=40% 2(12)+4(1)+2(16)

10.3.6 of carbon reacted with 0.8g of hydrogen to form a compounda)Determine the empirical formula of the compound formedb)Given thet the relative molecular mass of the compound is 88g,find its molecular formula.[Relative atomic mass:Cu,12;H,1]

a) Carbon HydrogenMass(g) 3.6 0.8No.of Moles(mol) 3.6÷12=0.3 0.8÷1=0.8Ratio of moles 3 8

Thus,the empirical formula of the compound is C3H8


b)(C3H8)n=88 (3(12)+8(1))n=88 n=8844

=2Thus,the molecular formula of the compound is C6H1611.Hydrogen gas is reacted with 20g of hot copper()oxide powders to produce solid copper and watera)Write the chemical equation for the reactionb)Calculate the maximum mass of solid copper formed[Relative atomic mass:Cu,64;O,16;H,1]

a)Cuo+H2→Cu+H2O

b)No.of moles of CuO=20g+(64+16)gmol-1

=0.25molRatio of moles CuO:Cu=1:1So Cu has 0.25mol.Mass of Cu=0.25mol x 64gmol-1

=16g12.Describe a laboratory experiment to determine the empirical formula of magnesium oxide and copper()oxideYour answer should include all the precautions and calculations involved’[Relative atomic mass:Mg,24;O,16;Cu,64;H,1]

Title Empirical formula of copper(II) oxide

Aim To determine the empirical formula of copper(II) oxide

Problem Statement

How does the formula of copper(II) oxide determine?

Hypothesis The empirical formula of copper(II) oxide can be determined by finding out the mass of copper and oxygen in a sample of copper(II) oxide

Apparatus U tubeStoppersGlass tubeCombustion tube with a small hole at the endRetort stand and clampSpatulaPorcelain dishBunsen burner


BalancePreparation for hydrogen gasThistle funnelFlat-bottomed flask

Material Hydrogen gas, H2

Copper(II) oxideAnhydrous calcium chloride, CaCl2

Wooden splinterPreparation for the hydrogen gasDilute hydrochloric acidZinc pieces

Variables Manipulated variable: Mass of copper oxideResponding variable: Mass of copper formedControlled / Fixed variable: An excess of hydrogen gas


1.State the basic principle of arranging the elements in the Periodic Table from its proton number

Increasing the proton number

2.State the physical properties of Group 1 -Atomic size increases-When going down the group,the number of shells occupied with electrons increases-Density increases-The increase in atomic mass is bigger than the increase in atomic radius.-Melting and boiling point increase-The metallic bond between the atoms becomes weaker down the group as the atomic radius increase.Thus less heat energy is required to overcome the weaker forces of attraction between the atoms during melting/boiling-Electropositivity of the metals increases-As atomic radius becomes larger down the group the force of attraction between the nucleus and the single valence electron becomes weaker.Hence,the elements lose the single valence electron more easily down the group.-Reactivity Increase-Reactivity increases because the atomic size increase,the valence electron in the outermost shell becomes further away from the nucleus.Hence,the atoms can easily donate the single valence electron to achieve the stable electron arrangement of the atom of noble gas.

3.State the physical properties of Group 17 -Reactivity Decrease-This is because the atomic size of halogen increases.Thus the outermost occupied shell of each halogen atombecomes further from nucleus.Thus,the strength to attract one electron into th valence shell by the nucleus become weaker.

4.State the changes in the atomic size and the electronegativity of elements across Period 3

Atomic size decreases from left to right-The proton number increases from left to right-The nuclei charge,positive charge in the nucleus increases-Nuclei attraction force between the nucleus and the valence electron increase-Valence electron becomes closer to the nucleu-Thus,atomic size becomes smaller

When across period 3 from sodium to argon,the electronegativity increases


5.State three special properties of transition elements

-The elements from group 3 to group 12 in the periodic table-Has high melting and boiling point-has high tensile strength

6.State the position of element X2039 in Periodic

Table.Explain your answer-Element X has an electron arrangement of 2.8.8.2.Hence,it is positioned at period 4 group 2.(Period=no of shells;Group=valence number)

7.When across Period 3 from sodium to argon,the atomic size decreases.Explain why.

-This is because the number of proton increases from left to right.This causes the positive charge in the nucleus to increase.The nuclei attraction force between the nucleus and the valence electron increase.The valence shell containing valence electron becomes closer to the nucleus.Hence,the atomic size decreases from sodium to argon.

8.When across Period 3 from sodium to argon,the electronegativity increases.Explain why.

-This is because the number of proton increases from left to right.This causes the positive charge in the nucleus to increase.The increase of proton causes valence shell containing valence electron to be closer to the nucleus.The more the proton number,the stronger the force to attract valence electron and electrons into the valence shell.Hence,the electronegativity increases across period 3

9.The reactivity of group 1 increases when going down the group.Explain why.

-Reactivity increases because the atomic size increase,the valence electron in the outermost shell becomes further away from the nucleus.Hence,attraction between nucleus and valence electron becomes weaker.Thus,the atoms can easily donate the single valence electron to achieve the stable electron arrangement of the atom of noble gas

10.The reactivity of group 17 decreases when going down the group.Explain why.

-This is because the atomic size of halogen increases.Thus,the outermost occupied shell of each halogen atom becomes further from nucleus.Thus,the strength to attract one electron into the valence shell by the nucleus becomes weaker.

11.Why helium gas in not reactive? -This is because it is a noble gas which has octect electron arrangement.Thus,it does not need to


receive or losses any electron making it not reactive.

12.X in an element from Group 1.X burnt in oxygen and the products is dissolved in water.What is the property of the solution formed?Explain why.

-The solution form is an alkaline solution.It reacts with acid to form salt and water.The solution formed has this characteristic because group 1 elements are alkali metals whereby its oxide can dissolve in water to form alkali(XOH).

13.Chlorine gas is dissolved in water.What can you observe is a piece of blue litmus paper is immersed into the solution formed?Explain why.

-Chlorine water changes the blue litmus paper into red then white.This happens because chlorine gas is an acidic gas and when it dissolves in water,its acidic properties are displayed and it becomes hydrochloric acid.The litmus paper hten changes into white as the solution has bleaching properties(HOCl)Cl2+H2O HCl+HOCl

14.W is an element from Group 1.Predict the chemical reaction of W with:a)waterb)oxygenState the observation and write the chemical equation involve.

Reaction With Observation EquationWater It reacts

quickly with water.The solution formed changes the red litmus paper into blue

2W + 2H2O 2WOH + H2

Oxygen It bums brightly with flame.White solid is produced and it dissolves in water.The solution formed changes red litmus paper blue

4W+O2

2W2O

W2O+H2O 2WOH

15.Describe a laboratory experiment to compare the reactivity of elements in Group 1:lithium,sodium and potassium.


16.Describe a laboratory experiment to compare the reactivity of chlorine,bromine and iodine in the reaction with iron wool.State the observation and write the chemical equations involve in reactions.

1.What is anion? -A negatively charged ion


2.What is cation? -A positively charged ion3.State two physical properties of ionic compounds4.State two physical properties of covalent compounds5.Explain why sodium chloride can conduct electricity in aqueous state but cannot conduct electricity in solid state.

-This is because in aqueous state the ions that made up sodium chloride are able to move freely in the solution.This means that there are charges moving in the solution.Hence,it can conduct electricity.However,in solid state,the ions are at fixed position in lattice.They are unable to move around freely.Thus,it cannot conduct electricity.

6.Magnesium chloride and hydrogen chloride are two compounds of chlorine.At room condition,magnesium chloride exists as a solid but hydrogen chloride exists as gas.Explain why.

Magnesium chloride

Aspects of view

Hydrogen chloride

Solid State at room temperatue

Gas

Ionic compound Type of compound

Covalent comppund

High Boiling point

Low

Ionic compound is held together by a strong bond called ionic bond.This means that more heat energy is needed to break the bonds and change the state of the compound.Hence,at a moderate room temperature it is in solid state

Inference Covalent compound is held together by weak intermolecular forces(Van-der-Waals force).This means that a small amount of heat energy is sufficient to change its state.Hence at a moderate room temperature it is in gas state


7.Describe the formation of ionic bond in sodium chloride,NaCl.

-A sodium atom has 11 electrons and it has an electron arrangement of 2.8.1.This electron arrangement is not stable.It needs to donate an electron to achieve an octet electron arrangement.When a sodium atom donates an electron,it will become sodium ion with the electron arrangement of 2.8.-Chlorine atom has 17 electros and it has an electron arrangement of 2.8.7.This configuration is unstable.It needs to receive one electron to become stable and achieve an octet electron arrangement.When a chlorine atom receive electron,it will become chloride ion with the electron arrangement 2.8.8.-When a sodium atoms reacts with a chlorine atom,an electron of the sodium atom is given to the chlorine atom.The positively charged ion Na+ will attract to the negatively charged ion,Cl- to form an ionic compound,sodium chloride, NaCl.This force enables the two ions to stick together through ionic bond.

8.By using example,describe the formation of covalent bond between element from Group 14 and element from Group 17.

-Example of formation:tetrachloromethane,CCl4 (Carbon-G14;Chlorine-G17)-The formula of tetrachloromethane molecule is CCL4.Carbon is in group 14 of the periodic table.It has four electron in its valence shell.In order to achieve the octet electron arrangement,each carbon atom needs another four more electrons to form an octet electron arrangement.-Chlorine atom is in group 17 of the periodic table.It has 7 valence electron.It needs one more electron to achieve the octet electron arrangement.-When one carbon atom share one electron with four chlorine atom,both carbon atom and chlorine atom can achieve a stable electron arrangement.This means that each chlorine atom share pair of electron with a carbon atom.This indicates single covalent bond.

9.Draw electron arrangement of the compound formed from the following elements.a)Nitrogen and hydrogenb)Carbon and oxygenc)Magnesium and chlorine


d)Carbon and hydrogene)Hydrogen and chlorinef)Sodium and oxygen

1.State the meaning of electrolyte -Substances that can conduct electricity when they are in molten or aqueous solution and undergoes chemical


changes.2.State the meaning of electrolysis -A process whereby compounds in molten or aqueous

solution are broken down into constituent element by passing electricity through them.

3.State three factors affecting electrolysis of an aqueous solution

-Position of ions in the electrochemical series-Concentration of ions in the electrolytes-Types of electrodes used in the electrolysis 1)Inert(Carbon/Platinum) 2)Active(Copper,etc.)

4.explain why solution of hydrogen chloride in water can conduct electricity but solution of hydrogen chloride in methylbenzene cannot conduct electricity?

Hydrogen chloride in water

Aspects Hydrogen chloride in methylbenzene

Yes Conduct electricity

No

This is because in water,hydrogen chloride is in the form of ions as it has dissociated.The hydrogen ion and chloride ion present in the aqueousbsolution carries positive and negative charges repectively.These charges are able to move freely.Hence,it is able to conduct electricity.

Inference This is because in methylbenzene,hydrogen chloride exists as neutral molecules.It has no charge.Hence,it is unable to conduct electricity.

5.By using example,explain how the following factors can determine the selective discharge of ions at the electrodes.a)types of electrodesb)concentration of the ions6.Describe the electrolysis of the molten lead()bromide

1.A crucible is filled with solid lead()bromide PbBr2 until it is half full.2.The apparatus are set up as shown.3.The solid lead()bromide,PbBr2 is heated util it is completely molten.


4.The circuit is switched on for about 20 minutes.The changes at the anode and the cathode are observed.5.The circuit is switched off and both electrodes are taken out from the electrolyte.The molten lead()bromide is carefully poured into a beaker.6.What is left at the bottom of the crucible is observed and recorded.

7.Describe the extraction of aluminium by electrolysis

1.Cryolite,Na2AlF6 is added to aluminium oxide to lower the melting point to about 8500C.2.The electrodes are made graphite.3.In the molten state,aluminium oxide will dissociate to aluminum ions and oxygen ions according to the folloeing equation: Al2O3 2Al3++3O2-

4.At the cathode: 4Al3++12e- 4Al At the cathode: 6O2- 3O2 +12e-

Overall Equation:4Al3+ + O2- 4Al + 3O2

5.Oxygen will be formed at the anode.It will burn the graphite electrode to form carbon dioxide.Hence,the graphite anode needs to be replaced occasionally.6.The aluminium is siphohed off as molten aluminium.

8.Draw the structure of Daniel Cell and explain how it can produce electricity

1.The solutions are connected through a salt bridge and porous pot

Negative terminal Positive terminalZinc CopperZinc metal becomes thinner because zinc atom from the electrode loses two electrons to form zinc ion.Zinc electrode dissolved.

Copper metal becomes thicker because the copper(ll) ions in the copper (ll) sulphate solution receive two electrons to form copper atoms which are later deposited at the copper electrode.

Zn Zn2+ + 2e- Cu2+ + 2e- Cu

Overal ionic equation:Zn + Cu2+ + Cu

The flow electrons from the zinc electrodes to the copper electrode results in the flow of alectrical current and thus


produces electricity.

9.Draw the structure of a dry cell and explain how it can produce electricity Negative terminal Positive terminal

Zinc CarbonZinc metal releases electrons and dissolves to form zinc ions.

Ammonium ions receive electrons to produce ammnia gas and hydrogen gas

Zn Zn2+ + 2e- 2NH4+ + 2e- 2NH3 + H2

1.Manganese(lV)oxide,MNO2 oxidises the hydrogen gas and minimizes the formation of gas bubbles at the carbon rod when the cell is in use 2MnO2 + H2 Mn2O3 + H2O2.The flow of electrons from the zinc metal casing (the external circuit) to the carbon rod results in the flow of electrical current and thus produces electricity.

10.Describe a laboratory experiment to extract lead from lead()oxide by using electrolysis

Anode Cathode2O2- O2 + 4e- Pb2+ + 2e- PbOverall ionic equation: 2Pb2+ + 2O2- 2Pb + O2

11.Describe a laboratory experiment to show that types of electrodes affecting the selective discharge of ions in electrolysis of copper()sulphate solution.12.You are given magnesium ribbon ,copper plate,magnesium nitrate solution ,copper()sulphate solution,connecting wires with crocodile clips,250cm3 beaker,voltmeter and porous pot.Construct a voltaic cell by using the above materialsExplain how the voltaic cell can produce electricity.Your answer must include observation and half equetions for reaction at anode and cathode13.Describe a laboratory experiment to construct the electromechanical series of magnesium,copper,zinc and lead


1.State the meaning of acid and alkali Acid -Chemical substances which ionizes in water to produce hydrogen ions,H+

Alkali-Soluble base2.What is the meaning of strong acid and weak alkali

Strong acid-Acid which ionizes completely with water to form hydrogen ion,H+(HCl)Weak Alkali-Alkali which partially ionizes in water to form


hydroxide ion,OH-(NH3)3.What is neutralization? -Reaction of an acid and a base4.What is salt? -A compound formed when the hydrogen ion,H+ from an

acid is replaced by ametal ion or an ammonium ion.5.What is precipitate reaction? -The method used to prepare insoluble salt where two

soluble salt solutions are mixed together.6.The pH value of ammonia in water is 9 but the pH value of solution of ammonia in trichlomethane is 7.Explain why pH value of two solutions is different

Ammonia in water

Aspects Ammonia in trichlomethane

9(alkaline) pH 7(neutral)This is because ammonia partially dissociates in water to form hydroxide ions.The presence of hydroxide ions causes the pH value to increase

Inference This is because ammonia exists as neutral molecules in trichlomethane.There is no presenc of either hydrogen ion or hydroxide ion that will change the pH value.Thus it is neutral.

7.80cm3 if distilled water is added to 20cm3 of 2.0 mol dm-3 solution of HCl.Find the molarity of the dilute solution.

M1V1=M2V2

2.0moldm-3(20/100dm3)=M2(100/100dm3)M2=0.4moldm-3

8.In titration ,40cm3 of 0.25 mol dm-3 potassium hydroxide,KOH solution is needed to neutralize 20cm3 of nitric acid,HNO3.Calculate the molarity of the nitric acid,HNO3

KOH + HNO3 KNO3 + H2O MaVa = a MbVb b

0.25(40) = 1 M(20) 1M=0.5moldm3

9.Given dilute nitric acid and dilute sulphuric acid have the same concentration of 0.5 mol dm-3.In neutralization experiment,20 cm3 of nitric acid is required to neutralize 20cm3 of sodium hydroxide solution but only 10cm3of sulphuric acid is required

-Sulphuric acid is a diprotic acid,when it dissociates in water to produce two hydrogen ions per mole-Nitric acid is a monoprotic acid,each of it dissociates to form one hydrogen ion.-Thus though same molarity of both acids are used to neutralize the same amount of acid with the same molarity,higher volume of nitric acid would be used as


to neutralize 20cm3 of sodium hydroxide solution.Explain why.

compared to the volume of sulphuric acid used because it nitric acid has half the number of hydrogen ion as compared to sulphuric acid.

10.Describe a chemical test to determine a given solution is an acid solution11.Describe a laboratory experiment to determine the concentration of sodium hydroxide by using titration process.You are given 0.2 mol dm-3 of dilute sulphuric acid,phenolphthalein,burette,pipette and conical flask12.You are given solid sodium chloride.Describe how to prepare sodium chloride solution of 0.2 mol dm-

3 in laboratory by using 250cm3 volumetric flask.13.Describe the preparation of zinc sulphate 14.Describe the preparation of lead()chloride 15.Describe the preparation of potassium nitrate16.Solid W is a salt.Describe the tests you would carry out to confirm the presence of zinc ions and nitrate ions in the salt?17.Solid X is a metal carbonate.Describe the test you would carry out to confirm that X consists of carbonate ions besides heating.18.You are given four test tubes filled with the solution consists of zinc ions,lead()ions,aluminium ions and magnesium ions respectively.Describe the tests you would carry out to confirm the ion that present in each test tube.19.You are given potassium chloride solution,lead()oxide powder and dilute nitric acid.Describe how you would prepare lead ()chloride salt


from the given materials.20.You are given diluye sulphuric acid,copper()nitrate solution and sodium carbonate solution.Describe how you would prepare copper()sulphate salt from given materials.

1.What is the meaning of alloy?State the aims of making alloys

-A mixture of 2 or more elements with a certain fixed composition in which the major component is metal(elements combined phusically)

2.What is the meaning of composite materials?State the

-A structural material that is formed bu combining two or more different substances such as metal,alloys,ceramics,glass and polymers.

Composite Components


components of the following composite materials:a)Reinforced concreteb)superconductorc)Fibre opticd)Fibre glasse)Photochromic glass

materialsReinforcement Concrete

Steel bars and concrete(cement,sand and small pebbles)

Superconductor

Yattrium oxide,barium carbonate,copper(II) oxide

Fibre Optics Silica,sodium carbonate,calcium oxide

Fibre Glass Glass fibre and polyster(a type of plastic)

Photochromic Glass

Glass and silver chloride or silver bromide

3.State the catalyst,temperature and pressure of the following process:a)Contact processb)Haber process

Process Catalyst Temperature Pressure ProductionHaber Process

Iron 400-4500C 150-300atp

Ammonia

Contact Process

Vanadium(v) oxide,V2O5

5000C 1-21tp Sulphuric acid

4.What is the meaning of polymers?Name the monomer of polythene and polyvinyl chloride

-Large molecules made up of many identical repeating sub-unit called monomers which are joined together by covalent bond

Monomer Synthetic PolymerEthene Polythene

Chloroethene Polyvinyl chloride,PVC


5.State four types of glass and their compositions.List the uses of each glass.

Type of Glass

Coponents Characteristics Uses

Soda-lime Glass

Silicon oxide,sodium oxide,calcium oxide

Good chemical durability,high thermal expansion coefficient,easy to make into different shapes,low melting point

Bottles,window panels,mirror,bulbs,flat galss,glass containers

Lead Crystal Glass

Silicon oxide,sodium oxide,lead oxide,potassium oxide,aluminium oxide

Soft and easy to melt,high density,high refractive index

Art objects,lens,prism,chandeliers

Borsilicate Glass

Silicon oxide,sodium oxide,calcium oxide,Boron oxide,aluminium oxide

Low thermal expansion coefficient,resistant to heat and chemical attact

Cooking utensils,lab glassware,automobile headlights

Fused Glass

Silicon oxide High heat resistant,high transparency,high melting point,resistant to chemical attact

Lab glassware,lenses,telescope,mirrors

6.What is ceramics?State the properties and list the uses of ceramics.

-Made from clay,such as kaolin.

Properties UsesStrong and hard Building materialsRust proof and chemicall resistance Kitchen wareHigh melting point Heat insulatorLonger lasting and pleasing Decorative itemsHard and not compressible Dental and medical usesElectric insulators Electrical items


7.Bronze is an alloy consists of copper and tin.Explain why bronze is harder than copper.

Bronze CopperTin atoms are added to the copper atoms arrangement.Tin atoms are bigger than copper atoms.As a result,the uniformity of the arrangement of copper atoms is disrupted and this prevents the layers of copper atoms to slide aver one another.

This made bronze harder than pure copper.

Copper atoms are arranged in an orderly manner and are packed close together.Because the copper atoms are all in the same size,it enables the layer of copper atoms to slide over easily when a force is applied.

This shows that pure copper is malleable and soft

8.Explain how acid rain is formed.Describe how acid rain causes environmental pollution.

Acid Rain:1.Release of of sulphuric dioxide from chimney of factories,and the burning of petrol in cars.2.The wind carries the pollutant around the globe.3.Formation of acid rain: a)Sulphur dioxide in air reacts with water and oxygen to form acid rain.

Effects:a)Acid rain coorodes buildings and metal structures.b)Flows into rivers and lakes causing water pollution. i)Lakes and rivers become acidic ii)Fish and other organism diec)Acid rain destroys trees in forestd)Causes soil pollution i)pH of the soil decreases ii)salts are leached out of the top soil iii)roots of trees are destroyed iv)plants die of malnutrition and diseases

9.Explain the industrial process involved in the manufacture of sulphuric acid.Write all the chemical equations involve.

Process named:Contact process

Steps involved:1.Sulphur is burnt in a furnace together with dry air to produce sulphur dioxide. S + O2 → SO2

2.Sulphur dioxide and air are passed over a converter to be converter to sulphur trioxide with the presence of: a)Catalytst:Vanadium(V)oxide,V2O5

b)Temperature:450-5000C c)Pressure:2-3 atp 2SO2 + O2 2SO3

3.Sulphur trioxide is dissolved in concentrated sulphuric acid to form a product


called oleum. SO3 + H2SO4 H2S2O7

4.Water is added to oleum to produce concentrated sulphuric acid H2S2O7 + H2O 2H2SO4

10.Explain the industrial process involved in the manufacture of ammonia gas.Write all the chemical equations involve.

Process named:Haber process

Steps involved:1.Nitrogen gas and hydrogen are mixed and scrubbed to get rid of impurities.2.One volume of nitrogen gas and three volume of hydrogen gas are compressed in the presence of 150-300 atp. N2 + H2 2NH3

3.Then,it goes to the converter.The conditions are: a)Catalyst:Iron b)Temperature:400-4500C4.The mixture of gas leaves the converter and is cooled until ammonia condense.Only 10% of the mixture will produce ammonia.5.The rest of the unsuccessful nitrogen and hydrogen gas are then pumpedback to the converter for another chance to react.6.The ammonia formed are then liquefied and separated to get a better yield.It is then stored under pressure tanks,

11.Describe a laboratory experiment to prepare ammonium sulphate(ammonium fertilizer)12.Describe a laboratory experiment to compare the hardness of brass and copper.

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