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Kansbag Chemistry Paper 3 Question Paper

Kansbag Chemistry Paper 3

Course:Secondary Level

Exam Year:2009

Name Admission Number Class

233/3
CHEMISTRY PRACTICAL
FORM 3
TIME: 2¼ Hours

KANSBAG PROJECTIONS FORM FOUR TERM 1 EXAMINATION 2009
Kenya Certificate of Secondary Education
CHEMISTRY PRACTICAL
PAPER 3
TIME: 2¼ Hours

INSTRUCTIONS
- Answer ALL questions in the spaces provided in the question paper.
- You are NOT allowed to start working with the apparatus for the first 15 minutes of the 2¼ hours allowed for this paper. This time is to enable you to read the question paper and make sure you have all the chemicals and apparatus that you need.
- All working MUST be clearly shown where necessary.
- Mathematical tables and electronic calculators may be used.

For Examiner’s Use Only
Question Max. Score Score
Q.1 15
Q.2 25
Total Score 40

1) You are provided with:
? Solution A; 0.11M hydrochloric acid
? Solution B; Containing 4.756g of basic compound V2X•10H2O in 250cm3 of water.
? Methyl orange indicator.
You are required to determine the relative formula mass of X.

Procedure: -
? Place solution A in a burette
? Pipette 25cm3 of solution B into a conical flask
? Add two drops of methyl orange indicator and titrate
? Repeat the procedure two, more times and complete the table below:

a) i)
I II III
Final burette reading (cm3)
Initial burette reading (Cm3)
Volume of solution A used (cm3)

ii) What is the average volume of solution A? (1mk)

b) Given that one mole of B reacts with 2 moles of A calculate the:-
i) Number of moles of the basic compound V2X•10H2O in the volume of solution B used (2mks)

ii) Concentration of solution B in moles per litre. (2mks)

iii) Relative formula mass of basic compound V2X•10H2O. (3mks)

iv) Relative formula mass of X (V=23.0; H=1.0; O= 6.0) (3mks)

2) You are provided with solid C. Carry out the tests below and write your observations and inferences in the spaces provided:
a) Dissolve all the Solid C provided in about 10cm3 of distilled water in a boiling tube. Shake well and filter the mixture. Retain both filtrate and the residue.
Observations Inferences
b) Divide the filtrate obtained into four portions:
i) To the first portion add 2 –3 drops of 1M lead (II) nitrate
Observation Inferences

ii) To the second portion add all Barium (II) chloride solution provided followed by about 2cm3 of 2M hydrochloric acid.
Observation Inferences
iii) To the third portion ad 3 drops of acidified potassium Manganate (VII) solution D.
Observation Inferences
iv) To the fourth portion add 5 drops of acidified potassium chromate (VI) solution E.
Observation Inferences
c) Place about half a spatula of the residue in a test-tube and heat strongly.
Observation Inferences
d) Place all the remaining residue in a clean test tube; add about 8cm3 of 2M nitric acid. Filter and divide the filtrate in 2 portions. (3mks)
Observation Inferences
i) To the 1st portion add aqueous sodium hydroxide drop wise until in excess. (3mks)
Observation Inferences
ii) To the 2nd portion ad aqueous ammonia drop wise till excess.
Observation Inference

Kansbag Chemistry Paper 3 Question Paper

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