A student investigated the temperature change in displacement reactions between metals and copper sulfate solution - AQA - GCSE Chemistry - Question 5 - 2018 - Paper 1
Question 5
A student investigated the temperature change in displacement reactions between metals and copper sulfate solution.
Table 2 shows the student's results.
Table 2
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Worked Solution & Example Answer:A student investigated the temperature change in displacement reactions between metals and copper sulfate solution - AQA - GCSE Chemistry - Question 5 - 2018 - Paper 1
Step 1
Plot the data from Table 2 on Figure 4 as a bar chart.
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Answer
To plot the data, the bar chart should have the y-axis labeled as 'Temperature increase in °C' ranging from 0 to at least 50. The x-axis will list the metals: Copper, Iron, Magnesium, and Zinc. Each bar should represent the temperature increase corresponding to each metal.
Copper: 0 °C
Iron: 13 °C
Magnesium: 43 °C
Zinc: 17 °C
Each bar must be of suitable height according to the temperature increases, and all bars should be clearly labeled.
Step 2
Give one reason why this conclusion is not correct.
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Answer
The conclusion is incorrect because the temperature of the reaction increases, indicating that energy is released to the surroundings, which is characteristic of an exothermic reaction, not an endothermic one.
Step 3
Describe a method to find the position of an unknown metal in this reactivity series.
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Answer
Add the unknown metal to copper sulfate solution.
Measure the temperature change of the solution upon adding the metal.
Compare the temperature change to the known temperature increases of copper, iron, magnesium, and zinc to determine its reactivity.
Alternatively, conduct the same experiment with an aqueous solution containing the other metals to observe which metal displaces copper, as a higher displacement indicates greater reactivity.
Step 4
Draw a fully labelled reaction profile for the reaction between zinc and copper sulfate solution on Figure 5.
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Answer
To draw the reaction profile for the reaction between zinc and copper sulfate, include the following:
The y-axis labeled as 'Energy' and the x-axis labeled as 'Progress of reaction'.
Start with the reactants at a certain height representing their energy level. Subsequently, draw a peak or activation energy point representing the energy barrier that the reactants must overcome. Finally, end with a lower energy level representing the products.
Clearly label the activation energy line and the overall energy change indicating the reactants and products.