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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 |... show full transcript
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.
Answer
To plot the data from Table 2 on Figure 4:
- Label the x-axis with the metals: Copper, Iron, Magnesium, and Zinc.
- Label the y-axis with the temperature increase in °C, ensuring the scale accommodates the maximum temperature increase of 43 °C.
- Draw bars for each metal:
- Copper: height 0 °C
- Iron: height 13 °C
- Magnesium: height 43 °C
- Zinc: height 17 °C
- Ensure the bars are spaced evenly and correctly represent the temperature increases.
Step 2
The student concluded that the reactions between the metals and copper sulfate solution are endothermic. Give one reason why this conclusion is not correct.
Answer
The conclusion is not correct because the temperature actually increases during the reaction, indicating that heat is released. This means the reaction is exothermic, not endothermic.
Step 3
Describe a method to find the position of an unknown metal in this reactivity series.
Answer
To find the position of an unknown metal in the reactivity series:
- Add the unknown metal to a solution of copper sulfate.
- Measure the temperature change before and after the reaction occurs.
- Compare the observed temperature change with the temperature changes recorded for copper, iron, magnesium, and zinc from Table 2.
- Rank the unknown metal in order of reactivity based on the temperature change observed relative to the known metals.
Step 4
Draw a fully labelled reaction profile for the reaction between zinc and copper sulfate solution on Figure 5.
Answer
To draw the reaction profile:
- Start with a vertical axis labeled 'Energy' and a horizontal axis labeled 'Progress of Reaction'.
- Draw a curve that rises to a peak, representing the activation energy, and then falls sharply.
- Label the peak as 'Activation Energy' and the starting point as 'Reactants' (indicating the combined energy of zinc and copper sulfate).
- The endpoint of the curve should be labeled 'Products', showing that the energy of the products is lower than the reactants, indicating an exothermic reaction.
- Clearly label the overall energy change as a downward arrow from reactants to products.