Page 54 - Spotlight A+ Form 4 & 5 Chemistry KSSM

Paper 3
1. In this experiment you are required to investigate the effect of different solutions of chloride salts on the heat
of precipitation of silver chloride, AgCl.
You are provided with the following materials:
L1 = 0.5 mol dm silver nitrate, AgNO solution
–3
3
L2 = 0.5 mol dm sodium chloride, NaCl solution
–3
L3 = 0.5 mol dm potassium chloride, KCl solution
–3
Carry out the experiment according to the following instructions:
1 Measure and pour 25 cm of L1 solution into a polystyrene cup.
3
2 Put the thermometer into the polystyrene cup containing L1 solution and leave it for 1 minute. Record
the initial temperature of L1 solution in Table 1.
3 Measure and pour 25 cm of L2 solution into another polystyrene cup.
3
4 Put the thermometer into the polystyrene cup containing L2 solution and leave it for 1 minute. Record
the initial temperature of L2 solution in Table 1.
5 Pour the L1 solution carefully and quickly into the polystyrene cup containing L2 solution.
6 Stir the mixture using a thermometer and record the highest or lowest temperature.
7 Repeat steps 1 to step 6 by replacing L2 solution with L3 solution.

Chloride salt solution L2 L3

Initial temperature of L1 solution (°C)
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Initial temperature of chloride salt solution (°C)

Highest/Lowest temperature of the mixture (°C)
Table 1
[**Complete Table 1 with reference to the Simulation experiments and sample results given]
Based on the experiment carried out:
1 State an inference based on the change in temperature in this experiment.
2 State the variable involved in this experiment:
(a) Manipulated variable
(b) Responding variable
(c) Fixed variable
3 Calculate the heat of precipitation of argentum chloride in both reactions:
–3
–1
–1
[Specific heat capacity of solution: 4.2 J g °C ; density of solution: 1 g cm ]
(a) Silver nitrate, AgNO solution + sodium chloride, NaCl (L1 + L2)
3
(b) Silver nitrate, AgNO solution + potassium chloride, KCl (L1 + L3)
3
4 State the operational definition of the heat of precipitation of silver chloride, AgCl.
5 Based on the results of the experiment, state the effect of different chloride salt solution on the
precipitation of argentum chloride, AgCl. Explain your answer.
2. In this experiment, you are provided with substances D1 and D2.
Part A Carry out the experiment according to the following instructions:
1 Put the appropriate quantity of D1 into a test tube.
2 Pour the dilute sulfuric acid, H SO into the test tube and warm the mixture slowly.
2
4
3 Carry out the experiments in Table 2 on the released gas.
4 Write the observations and inferences in Table 2.

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