A student investigated the temperature change produced when equal lengths of magnesium ribbon reacted with excess dilute sulfuric acid of different concentrations (labelled solutions A, B, C, D and E).
Five experiments were carried out.
Experiment 1
Using a measuring cylinder, 20 cm3 of sulfuric acid solution A was poured into a beaker. The initial temperature of the solution was measured. A length of magnesium ribbon was added to the solution and stirred. The highest temperature reached was measured.
Experiment 2
Experiment 1 was repeated using solution B instead of solution A. The initial and highest temperatures were measured as before.
Experiment 3
Experiment 1 was repeated using solution C. The initial and highest temperatures were measured.
Experiment 4
Experiment 1 was repeated using solution D. The initial and highest temperatures were measured.
Experiment 5
Experiment 1 was repeated using solution E. The initial and highest temperatures were measured.
Use the thermometer diagrams in the table, to record the initial and highest temperatures in each experiment.
solution of sulfuric acid | thermometer diagram | initial temperature / oC | thermometer diagram | highest temperature / oC | change in temperature / oC |
A |  |
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B |  |
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C |  |
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D | |
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E | |
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Work out the temperature change for each experiment and record the values in the table.
Draw a labelled bar chart of the results for Experiments 1, 2, 3, 4 and 5 on the grid below.
Use the results and observations to answer the following questions.
What type of chemical reaction occurs when magnesium reacts with dilute sulfuric acid?
i) Which Experiment produced the largest temperature change?
[1]
ii) Suggest why this Experiment produced the largest temperature change.
[1]
Predict the effect on the temperature changes that would happen if
i) equal masses of magnesium powder were used in the Experiments.
[1]
ii) 40cm3 of dilute sulfuric acid was used in Experiment 1.
[1]
iii) Explain your answer to (e)(ii).
[1]
Give one possible source of experimental error in this investigation.
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