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Chemistry Paper 2,Nov/Dec 2010  
Questions:   1 2 3 4 5 6 7 8   Main
General Comments
Weakness/Remedies
Strength







































































Question 4

(a) Consider the following reaction scheme:


(i)                          Give the:

I chemical formula of each of compounds A,B,C,D and E
II IUPAC names of compounds A,B,C,D and E.

   (ii)                State the type of reaction involved in the conversion of CH3CH2CH20H to:
                               I.           A;
                               II.          B;
                              III.         C. [13 marks]

(b) (i) Write a balanced chemical equation for the reactions in of chlorine with [ 4 marks]

I ethane,
II ethene.

        (ii) State the type of reaction exhibited in each of the reaction in 4(b)(i).            [4 marks]
(c)     (i) Give one product obtained from refining petroleum that is:
        I gaseous;
        II liquid;
        III solid.

(ii) State one use of each of the products mentioned in 4(c)(i). [ 6 marks]

(d)      Write a balanced chemical equation for the oxidation of glucose (C6H1206) in living organisms.
[ 2 marks]

                                                                                                                         

_____________________________________________________________________________________________________
OBSERVATION

The question was popular among the candidates and the performance was fair.
In(a)(i) I-II, candidates could not give the chemical formula and IUPAC names of the
compounds represented as A,B,C,D and E in the scheme. The expected answers from
candidates were as follows:
(i)      A - CH3CH2COOH
B - CH3 CH = CH2
C - CH3 CH2 COOCH2 CH3
o - CH3 CH2 COOH/CH3 CH2 OH
E - CH3 CH2 OH/CH3 CH2 COOH

  (ii)     A - propanoic acid
B - propene
C - ethyl propanoate
0- propanoic acid/ethanol
E - ethanol/propanoic acid

In(a)(iii).most candidates did not know that conversion to A is oxidation, B is dehydration and C is esterification in I -III.

In part(b)(i)1 and II, candidates correctly wrote balanced equation for the reaction of chlorine with ethane and ethene respectively thus:

  I.            C2H6 + Cl2 -'CH3 CH2 CI + HCL
  II.           CH2 = CH2 ----+ CH2 ClCH2 CL

In(b)(ii), candidates know that the type of reaction in (i) I and II were substitution and addition, respectively.

In part(c), candidates correctly gave one product obtained from refining petroleum that is gaseous, liquid and solid as butane/propane/ethane/methane/ethane,kerosene/dieselOil/lubricating oil/gasoline and asphalt/bitumen/paraffin wax respectively.

In part(d) only few candidates could write a balanced chemical equation for the oxidation of glucose in living organisms thus:

.

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