Get premium membership and access revision papers, questions with answers as well as video lessons.

Got a question or eager to learn? Discover limitless learning on WhatsApp now - Start Now!

Kcse 2015 Chemistry Paper 3 (Practical) Past Paper Question Paper

Kcse 2015 Chemistry Paper 3 (Practical) Past Paper

Course:Chemistry

Exam Year:2015

1. You are provided with:
• 2.0 g of substance A, labelled solid A.
• Solution B, 0.05 M hydrochloric acid.
• Methyl orange indicator.
You are required to determine the:
• solubility of substance A in water .
• relative formula mass of substance A.

PROCEDURE I
(i) Place 200 cm³ of tap water in a 250 ml beaker and keep it for use in step (vi).
(ii) Place all of substance A in a dry boiling tube.
(iii) Using a burette, measure 10.0 cm³ of distilled water and add it to the substance A
in the boiling tube.
(iv) While stirring the mixture in the boiling tube with a thermometer, warm the mixture
using a Bunsen burner, until the temperature rises to 65°C. Stop warming the mixture.
(v) Allow it to cool while stirring with the thermometer.
(vi) When the temperature drops to 60°C, start the stop watch/clock, place the boiling tube in the beaker with tap water prepared in step (i) above
(vii) Continue stirring and record the temperature of the mixture after two minutes, then thereafter record the temperature of the mixture after every one minute interval and complete table 1. Retain the mixture with the thermometer inside for use in procedure 11 below.

On the grid provided, plot a graph of temperature (vertical-axis) against time. (3 marks)

(a) Using the graph, determine the temperature (Ts) when 2.0 g of substance A completely dissolves in 10.0 cm³ of distilled water. (1 mark)

(b) Calculate the solubility of substance A in grams per 100 g water at temperature Ts. (2 marks)
PROCEDURE Il
Using a funnel, transfer all the mixture obtained from Procedure I into a 250 ml volumetric
flask. Rinse the boiling tube and the thermometer with about 20 cm³ of distilled water and add the rinses into the volumetric flask. Repeat the rinsing two more times. Add about 100 cm³ of distilled water to the volumetric flask, Shake until all the solid dissolves. Add more distilled water to the mark, Label this as solution A. Fill the burette with solution A, Using a pipette and pipette filler, place 25.0 cm³ of solution B, into a 250ml conical flask. Add three (3) drops or the indicator provided and titrate using solution A. Record your readings in table 2 below. Repeat the titration two more times and complete the table.

(a) Calculate the:
(i) average volume of solution A. used. (1 mark)
(ii) number of moles of hydrochloric acid, solution B used. (1 mark)
(b) Given that two moles of acid react with one mole of substance A,
calculate:
(i) number of moles substance A, used, (1 mark)
(ii) concentration of solution A in moles per litre;
(iii) concentration of solution A in g per litre;
(iv) relative formula mass of substance A.

2. You are provided with solid C. Carry out the following tests and record your observations and inferences in the spaces provided.
Place all the solid C in a boiling tube. Add about 15 cm³ of distilled water and shake until all the solid dissolves. Use 2 cm³ portions of the solution in a test-tube, for each of the tests in (a), (b), (c), (d), (e) and (f).
(a) Add aqueous sodium hydroxide dropwise until in excess.

(b) Add aqueous ammonia dropwise until in excess.

(c) Add 2 to 3 drops of solution D, aqueous sodium carbonate.
(Retain the remaining solution D for use in question 3)

(d) Add 2 to 3 drops of dilute hydrochloric acid.

(e) Add 2 or 3 drops of aqueous barium chloride.

(f) Add 2 or 3 drops of solution E, aqueous lead (II) nitrate.

3. You are provided with substance L. Carry out the following tests and record your observations and inferences in the spaces provided. Use about 2 cm³ portions of substance L in a test-tube for each of the tests, (a), (b), (c) and (d).
(a) Add 2 or 3 drops of bromine water.

(b) Add about 1cm3 of acidified potassium dichromate (VI). Warm the mixture.

(b) Add about 1 cm³ of solution D, aqueous sodium carbonate provided.

(d) Add the piece of magnesium ribbon provided.

Kcse 2015 Chemistry Paper 3 (Practical) Past Paper Question Paper

More Question Papers

Popular Exams