(a) Explain in terms of the kinetic theory why a tyre should not be overinflated.

 

(b)The following results were obtained at room temperature in an experiment to verify one of the gas laws using a glass syringe:

Pressure (P) of air in syringe (atm)	Volume (V) of air in syringe (cm\(^3\)	\(\frac{I}{V}\)
0.100	10.00	0.100
0.125	8.00	0.125
0.150	6.60	0.150
0.175	5.60	0.179
0.200	4.80	0.208
0.225	4.40	0.227

 

(i) Plot a graph of P against \(\frac{1}{v}\), using 1 cm to represent 0.01 atm on the vertical axis and 1cm to represent 0.02 unit on the horizontal axis.

(ii) Which of the gas laws is in agreement with the results?

 

(c) The flow chart below represents the stages involved in the manufacture of H\(_2\)SO\(_4\).

                                 +x          +Conc. H\(_2\)SO\(_4\)                +H\(_2\)O

S + O\(_2\) \(\to\) SO\(_2\)      \(\to\)     SO\(_3\)         \(\to\)          Y      \(\to\)    Conc H\(_2\)SO\(_4\)

    stage I           stage II                 stage III                 stage IV    

 

(i) Name the process represented by the chart.

(ii) Identify reactant X and product Y.

(iii) What are the operating temperature and pressure at stage II?

(iv) Mention the stage which requires a catalyst and state the catalyst used.

(v) Give the reason why the SO\(_3\) produced in stage II is not dissolved directly in water to form the acid

 

(d) When K\(_4\)Cr\(_2\)C\(_7\) dissolves in water, the following equilibrium is established:

Cr\(_2\)O\(^{2-}_{7(aq)}\) + H\(_2\)O\(_{(l)}\)   \(\to\)  2CrO\(^{2-}_{4(aq)}\)  + 2H\(_{aq}\)

(i) State the colour observed on adding a few drops of dilute H\(_2\)SO\(_4\) to the system.

(ii) Explain your answer in (d)(1).

 

(iii) What principle is applicable to this explanation?

 

(a)(i) State three methods of preparing salts, giving one example in each case of a salt so prepared.

(ii) What type of salt is each of the following? NaH\(_2\)PO\(_4\); (CH\(_3\)COO)\(_2\)Pb; KAI(SO\(_4\))\(_2\). 12H\(_2\)O.

 

(b)(i) Write an equation for the reaction between dilute HCI and a solution of AgNO\(_3\).

(ii) Explain why NaNO\(_3\) is preferred to AgNO\(_3\) in the preparation of oxygen by thermal decomposition of trioxonitrate (V) salts.

(iii) When silver wire was dipped into an aqueous solution of CuSO\(_4\), the wire remained intact but when the wire was replaced with zinc rod, the rod decreased in size. Give an explanation for this observation.

 

(c) When a sample of a crystalline salt X was exposed to air, there was a loss in mass.

(i) What phenomenon was exhibited by X?

(ii) Suggest two substances which X could be.

(iii) On heating 5.00 g of a fresh sample of X to constant mass, 1.80g was lost in the form of water vapour. Calculate the number of molecules of water of crystallization in one molecule of X. [H = 1.00; O = 16.00; Anhydrous form of X = 160 g mol\(^{-1}\)

a)(i) Give two uses of ammonia.

(ii) Name the process by which ammoniacal liquor can be obtained from coal and list two other products of the reaction

(iii) What type of reaction is involved in the conversion of ammoniacal liquor to (NH\(_4\))\(_2\)SO\(_4\) by dilute H\(_2\)SO\(_4\)?

(iv) Sketch and label an energy profile diagram to show the effect of presence of Pt/Rh on the reaction represented by the following equation: 4NH\(_3\) + 5O\(_2\)  \(\to\) 6H\(_2\)O + 4NO; \(\Delta\)H = —907 kJmol\(^1\)

 

(b) Rock salt is an impure form of sodium chloride.

(i) Outline a suitable procedure for preparing a pure sample of sodium chloride from rock salt.

(ii) State two methods that can be used to prepare chlorine from rock salt. Write an appropriate equation in each case.

 

(c) Lead pigments were used in a water colour painting which turned black after prolonged exposure to an air pollutant. The original colour was restored by using H\(_2\)O\(_2\) which converted the black substance to a simple, white lead (II) salt.

(i) Which pollutant turned the painting black?

(ii) Write the formula of the black substance

(iii) What is the white salt?

(iv) State the role of H\(_2\)O in the restoration process.

All your burette readings (initial and final), as well as the size of your pipette, must be recorded but no account or expeimental procedure is required. All calculations must be done in your answer book.

A is 0.125 mol dm\(^3\) H\(_2\)SO\(_4\). B is a solution containing X g dm\(^{-3}\) of NaOH.

(a) Put A into the burette and titrate it against 20.0 cm\(^3\) or 25.0 cm\(^3\) portions of B using methyl orange as indicator. Record the volume of your pipette. Tabulate your burette readings and calculate the average volume of A used. The equation for the reaction involved in the titration is H\(_2\)SO\(_4\) +2NaOH\(_{(aq)}\) \(\to\) Na\(_2\)SO\(_4\) + 2H\(_2\)O\(_{(l)}\)

(b) From your results and the information provided above, calculate the;

(i) amount of H\(_2\)SO\(_4\) in the average volume of A used

(ii) Concentration of B in mol dm\(^{-3}\)

(iii) value of X.

[H = 1: O = 16; Na = 23]

 

(c) Describe briefly a suitable laboratory procedure for obtaining pure water from the titration mixture. (No diagram is required)

 

Credit will be given for strict adherence to the 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 i.itne time they are made.

C is a sample of copper (II) tetraoxosulphate (VI) crystals. Carry out the following exercises on C. Record your observations and identify any gases evolved. State the conclusion you draw from the result of each test.

(a) Put half of C in a test tube and heat strongly

(b) Make solution of about 10 cm\(^{-3}\) with the sécond half of C and divide it into three portions

(i) To the first portion, add Sodium hydroxide solution in drops and then in excess. Heat the mixture

(ii) To the second portion, add aqueous ammonia in drops and then in excess followed by few drops of moderately concentrated HCI.

(iii) To the third portion, add all the zinc dust provided and stir thoroughly until there is a visible change.