Raw rubber is heated with sulphur in the manufacture of natural rubber.

i) What name is given to the process?

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ii) Why is the process necessary?

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iii) State one use of natural rubber

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The diagram below show a reaction that occur when a piece of sodium metal is placed in water.

State and explain the observations that would be made.

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A student accidentally mixed lead (II) Chloride and barium sulphate. Explain how the two solids can be separated to obtain pure samples of each.

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a) What is the general name given to the group in which elements A,B and C belong?

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b) Explain why element C has the lowest ionization energy.

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The diagram shows the radiation emitted by a radioactive sample.

Identify the radiations:

I.

D ..................................................................................................................................................................................................................................................................

II.

E ..................................................................................................................................................................................................................................................................

III.

F ..................................................................................................................................................................................................................................................................

The structure below represents a portion of a polymer.

a) Draw the structural formula of the monomer which is the repeating unit.

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b) State one commercial use of the polymer.

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b) Solution of sodium oxide in water conducts electricity. State how it conducts electricity.

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A certain organic compound on complete combustion gave out 9.9g of carbon (IV) oxide gas and 4.86g of water. Calculate the simplest formula of the organic compound

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The figure below shows interaction of carbon and oxygen in ‘dry ice’ (solid carbon (IV) oxide).

a) Which types of bonds are represented by letter :

i) G ....................................................................................................................................................................................................................................................

ii) H .....................................................................................................................................................................................................................................................

b) Explain why silicon (IV) oxide is a solid at room temperature while sulphur (IV) oxide is a gas at room temperature.

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Study the flow chart below and answer the questions that follow:

a) Name the;

i) Cation present in solid J

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ii) Anion in solid J

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b) Write an equation for the decomposition solid J.

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The graph below shows the change in temperature when 0.5M KOH Solution is added to 20cm3 of HNO3 acid

a) What does point M represent?

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b) Determine the molarity of the hydrochloric acid (HCl).

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The diagram below is a set up used in the laboratory to prepare oxygen gas.

i) Name the substance N

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ii) Write an equation showing the preparation of oxygen in the above arrangement.

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. iii) Name two solids which may be heated to obtain oxygen gas

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The figure below shows the cooling curve for water in gaseous state.

i) Using the same axis, draw a cooling curve obtained if the water used in the experiment was impure.

ii) Name the process taking place between a) Q and R

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b) S and T

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An ion of element W can be represented as shown below;

a) Identify the period in which element W belong.

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b) Write the electron arrangement of the ion of W.

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c) What would be the nature of aqueous solution of oxides of W.

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a) State one use of radioactive substances in medicine.

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b) The table gives the rate of decay for a radioactive element X.

Calculate the half life of the radioactive element X.

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Give the formula of the complex ion formed when Lead (II) hydroxide dissolves in excess sodium hydroxide solution.

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a) Identify two impurities removed during the extraction of aluminium. ...........................................................................................................................................................................................................................................................

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b) A solution of aluminium chloride in water is acidic. Explain. ...........................................................................................................................................................................................................................................................

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The diagram below represents part of a mercury cell study the diagram and answer the questions that follow:

a) Identify gas A

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b) If a current of 5 amperes is passed through brine in the mercury cell for 3 hours, calculate the volume of chlorine gas produced.( Molar gas volume=22.4dm³ at s.t.p; 1 Faraday=96,500 coulombs)

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a) Name the main ore from which lead is extracted.

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b) Write a chemical equation for reaction which takes place in the roaster when the above ore is converted into an oxide.

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c) State one use of lead metal.

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a) Zinc oxide reacts with both sodium hydroxide and dilute nitric (V) acid.

Write equation for the reaction between:

i) Zinc oxide and sodium hydroxide

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ii) Zinc oxide and dilute nitric (V)acid .

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b)Name the type of reaction that occur when zinc oxide reacts with nitric(V) acid.(1 mark).
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a) The ionic half equations for the reactions occurring at the electrodes are:

Draw an electrochemical obtained when the two half cells are combined. Indicate on the diagram the direction of electron flow.

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a) In an experiment on rates of reaction, a piece of magnesium with a mass of 0.1g was reacted with excess dilute hydrochloric acid. The experiment was then repeated with the same mass of magnesium, same volume of the acid but of different concentration, as indicated in the table below.

The results of the experiment are shown in the graph.

The hydrogen gas given off during the reaction and the volume obtained at different times are shown for each experiment by curves A and B on the graph.

i) Explain why the last part of curves A and B is horizontal.

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ii) Which curve shows a faster reaction? Explain.

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iii) Which experiment was used to produce curve A?

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In an experiment to determine the solubility of sodium chloride,13.2g of saturated sodium chloride solution at 18⁰C was evaporated to dryness and 3.6g of the salt remained. Determine the solubility of sodium chloride at 18⁰C.

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A wooden splint was slipped through a region of a particular flame in the laboratory and was burnt as shown in the diagram.

i) Name the type of flame the splint was slipped through.

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ii) Stating the region, explain why the splint was burnt the way it’s shown in the diagram.

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ii) State one disadvantage of using the above type of flame in the laboratory.

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The set up below was used to prepare and collect ethene gas. Study it and answer the questions below.

i) Name substance P.

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ii) Give the property of ethene that allows it to be collected as shown in the set up.

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iii) Name the reagent and one condition for conversion of ethane to ethene.

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In an experiment, nitrogen (II) oxide was bubbled through a solution of Iron (II) Sulphate in a test –tube. a) State and explain the observations that were made.

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b) Write an equation for the reaction that occurred.

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The set up below was used up in the Frasch process. Study it and answer the questions that follow.

a) Which substance is directed through pipe B? What is its role?

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b) State what the two layers in the settling tanks are.

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The equilibrium is established when calcium carbonate is heated in a closed vessel as shown below.

How would the position of equilibrium be affected if a small amount of aqueous potassium hydroxide is added to the equilibrium mixture? Explain.

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State and explain the observations made in the set up below.

Explain why burning magnesium continue to burn in nitrogen (II) oxide while it will extinguish a burning splint.

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Given the following bond energies;

Calculate the enthalpy change when methane reacts with excess chlorine.

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