CHEMISTRY PAPER 3 - KAPSABET BOYS 2019 TRIAL MOCK EXAMINATION

QUESTION 1

You are provided with:

• Solid A 5.0g (COOH)_2· H₂O
• Solution B 0.13M KMnO₄

Task

1. You are supposed to determine the solubility of A at different temperatures.
2. Determine the number of moles of water of crystallization in solid A.

PROCEDURE 1

1. Using a burette, add 4cm3 of distilled water to solid A in a boiling tube.
   1. Head the mixture while stirring with the thermometer to about 80⁰
   2. When the whole solid dissolves, allow the solution to cool while stirring with the thermometer
   3. Note the temperature at which crystals first appear and record this temperature in the table 1 below.
2. Using aburrete add 2cm³more into the content of the boiling tube and warm until the solid dissolve.
   1. Remove from the flame and allow the solution to cool in air while stirring.
   2. Record the temperature at which crystal first appear in table 1.
   3. Repeat procedure (b) 3 more times and complete table 1 below.
   4. Retain the content of the boiling tube for procedure II

Table 1

1. Draw a graph of solubility of solid A (vertical axis) against temperature (3mks)
2. From your graph determine the solubility of solid A at 60⁰C (1mk)

PROCEDURE II

1. Transfer the contents of the boiling tube into a 250ml volumetric flask.
   1. Add distilled water up to the mark
   2. Label this solution A
2. Using a clean pipette and a pipette filler, transfer 25ml of solution A into a conical flask.
   1. Warm the mixture up to 60⁰C
   2. Fill a burette with solution B
   3. Titrate B against the hot solution A until a permanent pink colour persist
   4. Read your results in Table 2 below
3. Repeat (b) 2 more times are record your results in the table 2 below.

TABLE 2

1. Calculate the average volume of solution B used (1mk)
2. Calculate the number of moles of B used (1mk)
3. Given 2 moles of KMnO₄ react with 5 moles of A, calculate the number of moles of A in 25cm³ (1mk)
4. Calculate the molarity of A (1mk)
5. Determine the molar mass of A (1mk)
6. Determine the value of X (1mk)
   (C=12, O=16 H=1)

QUESTION 2

You are provided with solid C. Use it to carry the test below. Dissolve the whole of C into 10cm3 of water and divide it into five portions.

1. To the 1^st portion add sodium sulphate solution.
   

   Observations	Inferences
   (1mk)	(1½mks)

2. To the 2^nd portion add Ammonia solution dropwise until in Excess.
   

   Observations	Inferences
   (1mk)	(1½mks)

3. To the 3^rd portion add sodium Hydroxide dropwise until in Excess.
   

   Observations	Inferences
   (1mk)	(1½mks)

4. To the forth portion add Lead (II) Nitrate solution
   

   Observations	Inferences
   (1mk)	(1½mks)

5. To the last portion add Barium Nitrate solution
   

   Observations	Inferences
   (1mk)	(1½mks)

QUESTION 3

You are provided with liquid D use it to carry the test below. Divide liquid D into four equal portions

1. To the 1^st portion add sodium hydrogen carbonate
   

   Observations	Inferences
   (1mk)	(1½mks)

2. To the 2^nd portion add acidified potassium manganite (VII) (KmnO₄)
   

   Observations	Inferences
   (1mk)	(1½mks)

3. To the 3^rd portion add Bromine water
   

   Observations	Inferences
   (1mk)	(1½mks)

4. To the last portion add potassium dichromate(VI0 and wrm.
   

   Observations	Inferences
   (1mk)	(1½mks)