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Alliance High School Chemistry Paper 3 Trial Examinations 2016 Question Paper

Alliance High School Chemistry Paper 3 Trial Examinations 2016

Course:Chemistry

Exam Year:2016

Alliance High School Trial Examinations
Chemistry
Paper 3
Form 4 Mock

1. You are provided with:
• 1.60g of solid A; a dibasic acid.
• Solution B containing 4.75g per litre of salt B.
• Aqueous Sodium Hydroxide, solution C.
• Phenolphthalein indicator.
You are required to prepare a solution of solid A and use it to determine the:-
• Concentration of Sodium Hydroxide, solution C.
• React salt B with excess Sodium Hydroxide and then determine the relative molecular mass of salt .
Procedure I
a) Using a burette, place 25.0cm³ of solution B in each of the two 250 ml conical flasks. Using a pipette and pipette filler, add 25.0cm of solution C to each of the two conical flasks. (The Sodium Hydroxide added is in excess). Label the conical flasks 1 and 2.
b) Heat the contents of the first conical flask to boiling and then let the mixture boil for 5 minutes. Allow mixture to cool.
c) Repeat procedure (b) with the second conical flask.
While the mixtures are cooling, proceed with procedure II.
Procedure II
a) Place all of solid A in a 250 ml volumetric flask. Add about 150 cm³of distilled water, shake well to dissolve the solid and then add water to make up to the mark. Label this as solution A.
b) Place solution A in a clean burette. Using a pipette and pipette filler , place 25.0 cm³ of solution C in a
250 ml conical flask. Add 2 drops of phenolphthalein indicator and titrate with solution A. Record your results in Table 1. Repeat the titration two more times and complete the table.

calculate the:-
i) Average volume of solution A used:
ii) Concentration in moles per litre of the dibasic acid in solution A; (2 marks)
(Relative molecular mass of A is 126).
iii) Moles of the dibasic acid used; (1 mark)
iv) Mole of Sodium Hydroxide in 25.0cm³ of solution C. (1 mark)
v) Concentration of Sodium Hydroxide in moles per litre. (2 marks)

Procedure III
Add 2 drops of Phenolphthalein indicator to the contents of the first conical flask prepared in procedure 1 and titrate with solution A. Record your results in Table 2. Repeat the procedure with the contents of the second conical flask and complete the table. (3 marks)

Calculate the:-
i) Average volume of solution A used;
ii) Moles of the dibasic acid used;
iii) Moles of Sodium Hydroxide that reacted with the dibasic acid. (1 mark)
iv) Moles of Sodium Hydroxide that reacted with 25.0 cm³ of salt B in solution B. (2 marks)
You are provided with: Magnesium ribbon labelled solid K 2.0M, Hydrochlori acid labelled solution P.
Stop clock/watch.
You are required to determine the rate of reaction between Magnesium and Hydrochloric acid at different concentrations.
Procedure
I. Place five test-tubes on a test-tube rack and label them 1,2,3,4 and 5. Using a 10cm³ measuring cylinder, measure out the volumes of 2.0M Hydrochloric acid, solution P a shown in table II and pour them into the corresponding test-tubes.
Wash the measuring cylinder and use it to measure the volumes of water as indicated in the table and pour into the corresponding test-tubes.
II. Cut out five pieces each of exactly l cm length of magnesium ribbon.
IIl.Transfer all of the solution in test-tube 1 into a clean 100cm³ beaker. Place one piece of Magnesium into the beaker and start a stop clock/watch immediately. Swirl the beaker continuously ensuring that the Magnesium is always inside the solution.
Record in the table the time taken for the Magnesium ribbon to disappear.
Wash the beaker each time.
IV. Repeat procedure-III for each of the solutions in the test-tubes 2,3,4 and 5 and complete the table.
a)

(5 marks)
(b) Plot a graph of rate of ''reaction. I( y-axis) against volume of solution P (3 marks)
(iii) - In terms of rate of reaction, explain the shape of your graph.

QUALITATIVE ANALYSIS
You are provided with solid E. Carry out the experiments below. Write your observations and inferences in the spaces provided.
a) Place all of solid E in the boiling tube. Add about 20 cm³ of distilled water and shake until all the solid dissolves, label the solution as solution E. Use solution E for experiments (i) and (ii).
i) To 2 cm³ of solution E, in a test - tube in each of experiments I, Il, III and IV add:
1. Two drops of aqueous Sodium Sulphate;
Observations.........................Inferences
H. Five drops of aqueous Sodium Chloride;
Observations.........................Inferences
Ill. Two drops of Barium Nitrate;
Observations.........................Inferences
IV. Two drops of aqueous Lead (ll) Nitrate;
Observations........................Inferences
V. To 2 cm³ of solution E, in a test - tube, add 5 drops of aqueous Sodium hydroxide. Add the piece of
Aluminium foil provided to the mixture and shake. Warm the mixture and test any gas produced with both blue and red litmus papers.
Observations........................Inferences

Alliance High School Chemistry Paper 3 Trial Examinations 2016 Question Paper

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