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KCSE CLUSTER TESTS 24

Chemistry Paper 3

1.

You are provided with:
- Solution A – 0.1M hydrochloric acid.
- Solution B- Containing 19.1g 1L of a basic compound B2X.10H2O.
You are required to determine the relative atomic mass of metal B in the formula B2X.10H2O
Procedure I
- Fill the burette with solution A upto the zero mark.
- Using a pipette and a pipette filler, place 25cm3 of solution B into a 250cm3 conical flask.
- Add three drops of methyl orange indicator and titrate.
- Record your results in table below.
- Repeat the procedure two or more times and complete table I

ii) Calculate the average volume of solution A used. (1mk)
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b) Given that one mole of B2X.10H2O reacts with 2 moles of hydrochloric acid, calculate the:
i) Moles of B2X.10H2O in the volume of solution B used. (2mks)
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ii) Concentration of solution B in moles per litre. (2mks)
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iii) Relative formula mass of B2X.10H2O (2mks)
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iv) Relative atomic mass of metal B in B2X.10H2O (Relative formula mass of X=156,
H=1.0, O=16.0) (2mks)
………………………………………………………………………………………
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………………………………………………………………………………………
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10 marks

2.

You are provided with:
- 2g of solid C- Oxalic ( .2 ) 2 2 4 2H C O H O
- Solution D -0.5M solution of oxalic acid (dibasic acid)
- Solution E – Sodium hydroxide solution.
You are required to determine
a) i) The molar heat of solution of solid C.
ii) The enthalpy of neutralization between oxalic acid solution D and Sodium
hydroxide solution E.
b) Calculate the heat of reaction of solid C with aqueous sodium hydroxide by applying
Hess’ law.
Procedure II
- Place 30cm3 of distilled water into a 100ml plastic beaker.
- Measure the initial temperature of the water and record it in table II below. Add all the solid C
at once.
- Stir the mixture carefully with the thermometer until all the solid dissolves. Do not break the
thermometer.
- Measure the final temperature reached and record it in table II below.

17 marks

3.

You are provided with solid F which is a mixture of two salts. Put all the solid F provided in a
boiling tube and add about 10cm3 of distilled water. Shake to dissolve. Divided the resulting
solution into four portions.
a) To the first portion, add 5 drops of aqueous sodium hydroxide and heat. Test for any gases
produced using a blue and red litmus papers.

9 marks

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