(a)(i) Give two differences between a conductor and an electrolyte.
(ii) State three applications of electrolysis.
(iii) Write equation for the reaction at each electrode when a dilute solution of sodium chloride is electrolysed using carbon electrodes.
(b)(i) What is an electrochemical cell?
(ii) Give two examples of primary cells.
(iii) Split the following equation into two balanced hall cell equations. Mte + Fe\(^{2+} \to Mg^{2+} + Fe\).
(c)(i) A current of 0.72 amperes was passed through dilute tetraoxosulphate (VI) acid for 3 hours 20 minutes. Calculate the quantity of electricity that was passed
(ii) If 1 dm\(^3\) of gas evolved at the cathode during the electrolysis of acidified water, what was the volume of gas evolved at the anode?
(d)(i) 20g of copper(II) oxide was warmed with 0.05 mole of tetraoxosulphate (VI) acid. Calculate the mass of copper (II) oxide that was in excess. The equation for the reaction: CuO\(_{(s)}\) + H\(_2\)SO\(_{4(aq)}\) ---> CuSO\(_{4(aq)}\) + H\(_2\)O\(_l\) [0 = 16 ; Cu = 64]
(ii) What type of reaction was involved in (d)(i)?
(a)(i) Define allotropy.
(ii) Name the allotrope of carbon used in gas masks.
(iii) Mention two other elements which exhibit allotropy apart from carbon.
(b) List the products of each of the following reactions:
(i) Heating coal in the absence of air.
(ii) Burning of candle wax in plentiful supply of air
(c)(i) State the two properties of carbon (IV) oxide which make it useful in extinguishing fire.
(ii) Write an equation for the reaction of carbon (IV) oxide with lime water
(iii) Calculate the volume of oxygen that was in excess if 150cm\(^3\) of carbon (II) oxide was burnt in 80cm\(^3\) of oxygen according to the following equation: 2CO\(_{(g)}\) + O\(_{2(g)}\) \(\to\) 2CO\(_{2(g)}\).
(d)(i) State how nitrogen can be obtained from ammonia gas.
(ii) Name the gaseous fuels obtained when steam and air are passed over red hot coke.
(iii) Which of the fuels in (d)(ii) has the lower heating ability? Give reason for your answer.
(a)(i) List two elements which react with steam at red heat to produce hydrogen.
(ii) Explain why an aqueous solution of potassium bromide turned reddish brown on bubbling chlorine through it.
(iii) Write an equation for the reaction in (a)(ii).
(b)(i) Name two types of chemical industry that use limestone as raw material.
(ii) Give one example of hygroscopic substances.
(iii) Copy and complete the table below.
|
Salt to be prepared |
Starting material |
Method of preparation |
| PbSO\(4\) | Pb(NO\(_3)_{2(ag)}\) | - |
| KNO\(_3\) | KOH | Neutralization |
| CaCl\(_2\) | CaCO\(_3\) | - |
| FeCl\(_3\) | Fe\(_(s)}\) | - |
| CuSO\(_4\) | CuO | - |
(c) In the contact process for the manufacture of tetraoxosulphate (VI) acid;
(i) State how sulphur (IV) oxide is obtained;
(ii) Write an equation for the reaction that takes place in the catalyst chamber;
(iii) Give the steps required to convert sulphur (VI) oxide to acid.
(d)(i) List two disadvantages of hard water.
(ii) Mention three methods which can be used to remove both permanent and temporary hardness in water at the same time.
(iii) State the role of alum and chlorine respectively in the purification of water for town supply.
Copy and complete the following table
| Element | Number of Neutrons | Electronic Configuration | Group in the periodic Table |
| \(^{23}_{11}Na\) | --- | 1s\(^{2}\)2s\(^{2}\)2p\(^{6}\)3s\(^{1}\) | 1 |
| \(^4_2He\) | 2 | ---- | --- |
| ---- | 7 | 1s\(^{2}\)2s\(^{2}\)2p\(^{2}\) |
---- |
(a) State two postulates of the kinetic theory of gases.
(b) Write two chemical properties that are common to both carbon (IV) oxide and sulphur (IV) oxide.
