A student investigated the addition of four different solids, A, B, C and D, to water. Five experiments were carried out.
Experiment 1
By using a measuring cylinder, 30 cm3 of distilled water was poured into a polystyrene cup and the initial temperature of the water was measured. 4 g of solid A was added to the cup and the mixture stirred with a thermometer. The temperature of the solution was measured after 2 minutes.
Experiment 2
Experiment 1 was repeated using 4 g of solid B.
Experiment 3
Experiment 1 was repeated using 4 g of solid C.
Experiment 4
Experiment 1 was repeated using 4 g of solid D.
Experiment 5
A little of the solution from Experiment 4 was added to a little of the solution from Experiment 2 in a test-tube. The observations were recorded.
Observations: A fast reaction. Vigorous effervescence and bubbles produced.
Use the thermometer diagrams for Experiments 1-4 to record the initial and final temperatures in Table 4.1. Calculate and record the temperature difference in Table 4.1.
Table 4.1
experiment | temperature / °C | final temperature / °C | difference / °C |
1 |
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2 |
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3 |
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4 |
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Draw a labelled bar chart of the results to Experiments 1, 2, 3 and 4 on the grid below.
Use the results and observations from Experiments 1-5 to answer the following questions.
i) Which solid dissolves in water to produce an exothermic reaction?
[1]
ii) Give a reason why you chose this solid.
[1]
Which Experiment produced the largest temperature change?
Predict the temperature change that would happen if
i) 8 g of solid B were used in Experiment 2
[1]
ii) 60 cm3 of water was used in Experiment 4
[1]
iii) Explain your answer to (e)(ii)
[2]
Suggest an explanation for the observations in Experiment 5.
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