(a)(i) What is meant by cracking of petroleum fractions?
(ii) Write an equation for the laboratory preparation of ethene from ethanol.
(iii) Give one chemical test to distinguish between ethane and ethene.
(b)(i) Name the class of carbohydrates to which starch and cellulose belong.
(ii) What process is used for isolating ethanol from the other products of fermentation of sugar?
(iii) Name the organic product of the reaction between ethanol and sodium
(iv). Write the structural formula of 2-chloroethanol.
(c) State the reason why:
(i) benzene produces more soot than ethene on burning in excess air;
(ii) ethanoic acid has a higher boiling point than methanoic acid;
(iii) sodium chloride is used during the manufacture of soap.
(d) Give one use of: (i) ethyne (ii) coal (iii) carbon black
(a)(i) List three characteristic properties of transition metals
(ii) 0.45g of a metal M was deposited when a current of 1.8 amperes was passed for 12.5 minutes through a solution containing M\(^{2+}\). Calculate the relative atomic mass of M. [1 Faraday = 96500 C]
(iii) Give the reason why copper-plated iron corrodes easily when the surface is scratched.
(b)(i) State the law of definite proportions (constant composition).
(ii) Describe in outline, an experimental procedure for determining the proportion of oxygen in a given sample of copper(II) oxide.
(iii) Write an equation to show how copper (II) oxide can be obtained directly from copper (II) trioxonitrate (V)
(a) Name one laboratory apparatus/set-up for:
(i) determining the heat of neutralization:
(ii) decomposing water into hydrogen and oxygen.
(b) Outline a suitable procedure for distinguishing between glucose and cellulose using
(i) one physical test apart from tasting.
(ii) one chemical test.
(c) Draw a labelled sketch to illustrate the separation of a mixture by sublimation.
(ii) Give two examples of substances that are sublime.
(d)(i) Mention one salt which produces brown fumes on being heated strongly
(ii) What is the action of the brown fumes mentioned in (i) above on litmus.
(iii) Give one reason why it is not advisable to collect nitrogen by displacement of air [N - 14].
Credit will be given for strict adherence to instructions, for observations precisely recorded, and for accurate inferences. All tests, observations, and inferences must be clearly entered in your answer book, in ink, at the time they are made.
C and D are samples of two simple salts. Carry out the following exercises on them. Record your observations and state the conclusion you draw from the result of each test.
(a)(i) Put half of C in a test tube and add about 5cm\(^3\) of distilled water. Test with litmus.
(ii) Put the rest of C in a test tube and add about 5cm\(^3\) of dilute hydrochloric acid. Identify any gases evolved.
(b)(i) Put half of D in a test tube. Add about 5cm\(^3\) of sodium hydroxide solution and warm. Identify any gases evolved.
(ii) Put the rest of D in a test tube and add about 5cm\(^3\) of distilled water. Mix thoroughly. Add about 2cm\(^3\) of barium chloride solution, followed by dilute hydrochloric acid in excess.
All your burette readings (initial and final), as well as the size of your pipette, must be recorded but on no account of experimental procedure is required. All calculations must be done in your answer book.
A is 0.50 mol dm\(^{-3}\) hydrochloric acid. B is 0.025 mol dm\(^{-3}\) of a trioxocarbonate (IV) salt.
(a) Put A into the burette and titrate with 20.0cm\(^{-3}\) or 25.0 cm\(^{-3}\) portions of B using methyl orange or screened methyl Orange indicator. Record the volume of your pipette. Tabulate your burette readings and calculate the average of A used.
(b) From your results, calculate the mole ratio of acid to trioxocarbonate (IV) in the reaction, expressing your answer as a whole number ratio of one.
(c) Given that B contains 7.2g dm\(^{-3}\) of the hydrated trioxocarbonate (IV) salt, calculate the:
(i) concentration of anhydrous salt in B in g dm\(^{-3}\) [Molar mass of anhydrous salt in B = 106g]
(ii) percentage of water of crystallization in the hydrated salt.
