The grid below represents part of the periodic table. Study it and answer the questions that follow. The letters do not represent the actual symbols of elements.

a) i) An element V has atomic number 7. Indicate the position of V on the grid. (1 mark)

ii) Explain why the atomic radius of E is bigger than that of R. (2 marks)

iii) Elements R, W and X belong to the same group. Which of the elements is the most reactive? Explain your answer. (2 marks)

b) i) Give the most reactive metal and state why. (2 marks)

ii) Write the formula of the compound formed when B reacts with E. (1 mark)

c) An element Z consists of isotopes of masses 10 and 2 with percentage composition 18.7% and 81.3% respectively. Determine the relative atomic mass of Z. (2 marks)

a) During an experiment a student added soap solution to separate samples of water until lather was formed. Below is a table showing the volumes of soap solution that was required to form lather with 100cm³ of each sample of water before and after boiling the samples.

i) State the most likely source of water sample X. (¹/₂ mark)

ii) Name a salt most likely to be present in water sample Y. (¹/₂ mark)

iii) Write an equation for the reaction that may have occurred in water sample Z when it was being boiled. (1 mark)

b) Study the flowchart below and answer the questions that follow.

i) Name the types of reaction that occurs in steps I and II

Step I _____________________________________________________ (¹/₂ mark)

Step II _____________________________________________________ (¹/₂ mark)

ii) What conditions are necessary for the reaction you have named in (i) above? (1¹/₂ mark)

iii) Write a chemical equation for the reaction that takes place in step IV (1 mark)

iv) Why is substance R used in some soaps? (¹/₂ mark)

c) The flow diagram below shows some of the steps followed during the industrial manufacture of a detergent.

i) What is a detergent? (1 mark)

ii) Identify reagents V and W (2 marks)

i) Reagent V

ii) Reagent W

iii) Write an equation for the reaction that may occur when the detergent is added to water containing magnesium ions. (1 mark)

iv) State one advantage of using the above detergent. (1 mark)

The flow chart below represents the main steps in the manufacture of sodium carbonate.

a) Name the substances labelled A – D (2 marks)

A_______
B_______
C_______
D_______

b) Identify substance E and write a chemical equation for the reaction in the kiln. (2 marks)

Substance E

Equation_____

c) Explain the need of large amounts of water in this experiment. (1 mark)

d) Name the by – products that are recycled. (1 mark)

e) Why is recycling important? (1 mark)

f) The flow diagram below shows several reactions starting with carbon.

i) State the observation made when gas M is passed over heated copper (II) oxide. (1 mark)

ii) State one application of solid Z. (1 mark)

iii) Write an equation for the formation of gas M from gas W. (1 mark)

iv) Explain the precaution to be taken in (iii) above. (2 marks

Use the standard electrode potentials given below to answer the questions that follow.

Ag+(aq)	+	e-	→	Ag(s)	+ 0.80	………………	(i)
Cu2+(aq)	+	2e-	→	Cu(s)	+ 0.34	………………	(ii)
Pb2+(aq)	+	2e	→	Pb(s)	- 0. 13	………………	(iii)
Zn2+(aq)	+	2e-	→	Zn(s)	-0.76	………………	(iv)

a. Select two half – cells which when combined will give the lowest workable cell (lowest e.m.f) (1 mark)

b. Can a solution of silver nitrate be stored in a container of zinc? (2 marks)

c. An iron jug was electroplated using Chromium. The chromium electrode and iron jug were thoroughly cleaned and weighed before being dipped into the electrolyte. Why was cleaning necessary? (1 mark)

d. A current of 0.75 Amperes was passed through the solution for one hour and four minutes. The mass of chromium deposited on the jug was 0.52g (1F = 96500C, Cr = 52)

i) Calculate the quantity of electricity passed. (3 marks)

ii) How many moles in chromium were deposited? (1 mark)

iii)Calculate the quantity of electricity in coulombs required to deposit one mole of chromium. (2 marks)

iv) Deduce the charge of the Chromium ion. (2 marks)

a) Fractional distillation of liquid air usually produces nitrogen and oxygen as the major products.

i) Name one substance that is used to remove carbon (IV) oxide from the air before it is changed into liquid. (1 mark)

ii) Describe how nitrogen gas is obtained from the liquid air.

(Boiling points Nitrogen = -196⁰ C, Oxygen = - 183⁰ C) (3 marks)

b) Study the flow chart below and answer the questions that follow.

i) Name element M (1 mark)

ii) Why is it necessary to use excess air in step IV? (1 mark)

iii) Identify gas Q. (1 mark)

iv) Write an equation for the reaction in step VII. (1 mark)

v) State one use of ammonium nitrate. (1 mark)

c) State and explain the observations that would be made if a sample of sulphur is heated with concentrated nitric (V) acid. (3 marks)

a) In an experiment to determine the enthalpy change for the displacement reaction:

Mg_(s) + Zn²⁺_(aq) → Mg²⁺_(aq) + Zn_(s)

25cm³ of 1M Zinc chloride solution was placed in a plastic beaker. The temperature of the solution was recorded every half minute for 1½ minutes. At exactly two minutes, excess zinc powder was added and temperature of the mixture recorded every half minutes. The mixture was stirred continuously with a thermometer during the experiment. The results obtained are given below.

i) Plot a graph of temperature (vertical axis) against time. (4 marks)

ii) Determine the maximum temperature rise from the graph. (1 mark)

iii) Calculate the molar enthalpy of displacement of Zinc (II) ions by magnesium.

Take density of final solution = 1g/cm³, specific heat capacity of solution = 4.2 kJ/kg/⁰C.(3 marks)

b) i) State Hess’ law (1 mark)

ii) Using the following equations to determine the heat of formation of butane.

C_(s) + O_{2 (g)} → CO_{2 (g)} $∆H$₁ = - 393kJ/mol

H_{2 (g)} + $\frac{1}{2}$O_{2 (g)} → H₂O _(g) $∆H$$∆H$₂ = - 286 kJ /mol

C₄H_{10 (g)} + $\frac{13}{2}$O_2(g) →4CO_2(g) + 5H₂O_(l) $∆H$₃ = - 2877 kJ /mol

I. Draw an energy cycle diagram for the formation of butane. (2 marks)

II. Calculate the heat of formation of butane. (2 marks)

The diagram below is a flow chart for the extraction of copper. Study it and answer the questions that follow.

a) Write the formula of the major ore of copper metal. (1 mark)

b) Name process II. (1 mark)

c) Give an equation for the reaction that occurs in stage III. (1 mark)

d) Explain what happens in stage IV. (2 marks)

e) Write half-cell equations occurring at the anode and cathode in stage VII. (2 marks)

f) Draw a simple diagram showing the set-up that is used in electrolytic purification of copper. (3 marks)