A student investigated the reaction between two different solids, C and D, and excess dilute hydrochloric acid.
Five experiments were carried out.
Experiment 1
A measuring cylinder was used to pour 30 cm3 of dilute hydrochloric acid into a polystyrene cup. The temperature of the dilute hydrochloric acid was measured. 1 g of solid C was added to the dilute hydrochloric acid and the mixture stirred with a thermometer.
The maximum temperature reached by the liquid mixture was measured.
Experiment 2
The polystyrene cup was emptied and rinsed with water.
Experiment 1 was repeated using 2 g of solid C.
Experiments 3 and 4
Experiment 2 was repeated using 3 g and then 5 g of solid C.
Complete the first column in the table.
Use the thermometer diagrams to record the results in the table below.
Complete the final column in the table.
experiment | mass of solid C / g | thermometer diagram | initial temperature of acid / oC | thermometer diagram | maximum temperature reached / oC | temperature difference / oC |
1 |
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2 |
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3 |
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4 |
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Experiment 5
Experiment 1 was repeated using solid D. Use the thermometer diagrams to record the results in the spaces below.
initial temperature of acid | final temperature of liquid mixture |
initial temperature of dilute hydrochloric acid = .................... °C
final temperature of liquid mixture = .................... °C
temperature change = .................... °C
Plot the results for Experiments 1, 2, 3 and 4 on the grid and draw a straight line graph.
i) From your graph, deduce the temperature of the solution when 6 g of solid C is added to 30 cm3 of dilute hydrochloric acid. Show clearly on the grid how you worked out your answer.
.............................. °C
[2]
ii) From your graph, deduce the mass of solid C that would give a temperature rise of 9°C when added to 30 cm3 of dilute hydrochloric acid.
..............................
[2]
What type of chemical process occurs when solid D reacts with dilute hydrochloric acid?
Suggest the effect on the results if Experiment 3 was repeated using 60 cm3 of dilute hydrochloric acid.
Predict the temperature of the solution in Experiment 4 after 1 hour. Explain your answer.
When carrying out the experiments, what would be one advantage and one disadvantage of taking the temperature readings after exactly one minute?
advantage ....................................................................................................
disadvantage ....................................................................................................
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