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6.1 - SPECIMEN SET C2 Q3 Answers

3) A student investigated the rate of the reaction between magnesium and dilute hydrochloric acid.
The student used the apparatus shown in Figure 4 to collect the gas produced.
3.1) Outline a plan to investigate how the rate of this reaction changed when the concentration of the hydrochloric acid was changed.
  • Describe how you would do the investigation and the measurements you would make.
  • Describe how you would make it a fair test.
You do not need to write about safety precautions. [6 marks]
3.2) Figure 5 shows the gas syringe during one of the experiments.
​What is the volume of gas collected? [1 mark]
​Tick one box.
3.3) ​Figure 6 shows the student’s results for one concentration of hydrochloric acid.
Table 2 shows the student’s results when the concentration was two times greater than the results on Figure 6.
Plot the results in Table 2 on the grid in Figure 6. Draw a line of best fit. [3 marks]

3.4) Give one conclusion about how the rate of reaction changed when the concentration of hydrochloric acid was changed. [1 mark]

3.5) Figure 7 shows volume of gas produced against time for the reaction between magnesium and ethanoic acid.
Draw a tangent to the curve at 20 seconds.
Determine the rate of the reaction at 20 seconds by calculating the gradient of the tangent.
Give the unit. [4 marks]

Rate of reaction = ________________________
Unit =  _______________________________

3.6) Explain, in terms of particles, why the rate decreases during the reaction between magnesium and ethanoic acid. [2 marks]​

​​​​(Total for Question 3 = 17 marks)

Answers