a) State Graham’s law of diffusion. (1 mark)

b) 48cm³ of an oxide of nitrogen diffused through a porous plug in the same time it took 159cm³ of helium to diffuse through the same plug under similar conditions. What is the molecular mass of the oxide? (He = 4, N = 14). (2 marks)

a) Hydrogen sulphide gas is a strong reducing agent. State and explain the observations made when this gas is bubbled through a solution of iron (III) chloride. (2 marks)

b) Write the chemical equation involved in the reaction. (1 mark)

The table below gives the first ionization energies of the alkali metals.

a. Define the term ionization energy. (1 mark)

b. Which of the three metals is the least reactive? Give a reason. (2 marks)

Describe how you would prepare a pure dry sample of lead (II) chloride starting with lead (II) carbonate (3 marks)

The diagram below shows part of the structure of a polymer.

a. Write the structural formula of the monomer. (1 mark)

b. If a sample of the polymer has a mass of 28125g, estimate the number of molecules of the monomers in it. (C = 12.0, H = 1.0, Cl = 35.5) (2 marks)

a) Using dots () and crosses (×), show the bonding in hydroxonium ion (H = 1, O = 8 ) (2 marks)

b) Chlorine gas has a very low melting and boiling points, yet the atoms are joined by strong covalent bonds. Explain. (1 mark)

a) Complete the nuclear equation below (1 mark)

b) Copper – 64 has half- life of 12.8 days. What mass of copper – 64 will remain after 51.2 days, Starting with 20g of the isotope. (2 marks)

Compound Q was reacted with hydrogen chloride to produce compound R whose molecular structure is shown below.

CH₃CH₂CH (CH₃) CHClCH3

a. Name compound Q. (1 mark)

b. State one laboratory test of compound Q. (1 mark)

c. Which type of reaction takes place between compound Q and hydrogen chloride? (1 mark)

The table below gives the number of electrons, protons and neutrons in substances x, y and z.

Study it and answer the questions that follow.

a. Which letter represents an ion? (1 mark)

b. Which of the substances are isotopes? Give a reason. (2 marks)

Nitrogen and hydrogen react to form ammonia gas as shown in the following equation.

$∆$H is negative

a. The figure below shows how the percentage of ammonia gas in the equilibrium mixture changes with temperature.

Explain why the percentage of ammonia gas changes as shown in the figure. (2 marks)

b. On the axes below sketch a graph showing how the percentage of ammonia gas in the equilibrium mixture changes with pressure. (1 mark)

Distinguish between the terms deliquescent and efflorescent as used in chemistry. (2 marks)

The flow chart below shows some processes involved in the industrial extraction of zinc metal.

a. Name one ore from which zinc is extracted. (1 mark)

b. Write the equation for the reaction taking place in unit II. (1 mark)

c. State two uses of zinc metal. (1 mark)

The diagram below represents a set up that was used to show that part of air is used during burning.

a. Given that the phosphorous used was in excess, draw a diagram of the set up at the end of the experiment. (2 marks)

b. Suggest one modification that should be made on the apparatus if the percentage of air used is to be determined. (1 mark)

Study the scheme below and answer the questions that follow.

a, Identify solution Q and solid R.

i. Solution Q. (1 mark)

ii. Solid R. (1 mark)

b. Write an ionic equation for the reaction between solution Q and excess aqueous ammonia. (1 mark)

The equation below shows the molar enthalpies of combustion of carbon, hydrogen and methane.

C_(s) + O_{2 (g)} → CO_{2 (g) $∆$}H _c = -393.5kJ/mol.

H_{2 (g)} + $\frac{1}{2}$O_{2 (l)} → H₂O_(l) $∆H$ _c = - 285 kJ/mol

CH_{4 (g)} + O_{2 (g)} → CO_{2 (g)} + H₂O _(g) $∆H$ _c = - 890kJ/mol

Use an energy cycle diagram to calculate the heat of formation of methane. (3 marks)

Describe how the pH of the soil sample can be determined in the laboratory.

During the electrolysis of aqueous silver nitrate, a current of 5.0A was passed through the electrolyte for 3 hours.

a) Write the equation for reaction which took place at the anode. (1 mark)

b) Calculate the mass of silver deposited. (Ag = 108, 1F = 96500C) (2 marks)

The table below shows the number of valence electrons of the elements P, Q and R.

a) Explain why P and R would not be expected to form a compound. (1 mark)

b) Write an equation to show the effect of heat on the carbonate of R. (1 mark)

c) Write the formula for the most stable ion of Q. (1 mark)

Copper is listed on the periodic table as having a relative atomic mass of 63.55. Two isotopes of copper exist with relative masses of 62.93 and 64.93. Find the percentage abundance of each isotope.

In an experiment, soap solution was added to three separate samples of water. The table below shows the volumes of soap solution required to form lather with 100cm³ of each sample of water before and after boiling.

a. Which water is likely to be soft? Explain. (2 marks)

b. Explain the change in volume of soap solution used in sample III. (1 mark)

What volume of 0.5M hydrochloric acid solution will neutralize 20cm³ solution of sodium carbonate containing 5.3g of anhydrous sodium carbonate per litre of solution?

(Na = 23.0, C = 12.0, O = 16.0, H = 1.0, Cl = 35.5) (3 marks)

3.1g of an organic compound containing carbon hydrogen and oxygen only produced 4.4g of carbon (IV) and 2.0g of water on complete combustion.

a) Determine its empirical formula. (2 marks)

b) Determine its molecular formula if its formula mass is 62. (1 mark)

A mixture contains sodium chloride, sugar and camphor. The table below shows the solubility of three solids in different liquids.

Explain how sugar can be obtained from a mixture of the three. (3 marks)

In the industrial preparation of oxygen, state:

a) How dust particles are removed from air. (1 mark)

b) Why CO₂ is removed before the mixture is cooled to -25⁰ C. (1 mark)

A beaker contained 75.0cm³ of aqueous copper (II) sulphate at 23.7⁰ C. When scrap iron metal was added to the solution the temperature rose to 29.3⁰C

a) Write an ionic equation for the reaction that took place. (1 mark)

b) Given that mass of copper deposited was 5.83g, Calculate the molar enthalpy change in kJ/mol. (specific heat capacity of solution = 4.2J/g/K, density of solution = 1.0g /cm³, Cu = 63.5) (2 marks)

a) State the Charles’ law. (1 mark)

b) The volume of a sample of nitrogen gas at a temperature of 18⁰C 1.0 X 10⁵ Pascal’s was 3.5 x 10^-2m³. Calculate the temperature at which the volume of the gas would be 2.8 × 10^-2m³ at 1.0 × 10⁵ Pascals. (2 marks)

a) When brine is electrolyzed using inert electrodes, chlorine gas is liberated at the anode instead of oxygen. Explain this observation. (2 marks)

b) Name the product formed at the cathode. (1 mark)

Describe how the percentage mass of copper in copper carbonate can be determined.