A student investigates the reaction of small pieces of zinc with dilute hydrochloric acid at 25°C. The dilute hydrochloric acid is in excess.

1. (a)Complete the equation for this reaction by adding state symbols. Zn(......) + 2HCl(......) → ZnCl₂(aq) + H₂(......)[2]
2. (b)(i)Fig. 3.1 shows the volume of hydrogen released as the reaction proceeds. [Figure 3.1] Deduce the time taken from the beginning of the experiment to collect 39cm³ of hydrogen. time ... s[1]
3. (b)(ii)The student repeats the experiment using dilute hydrochloric acid with a higher concentration. All other conditions stay the same. Draw a line on the grid in Fig. 3.1 to show how the volume of hydrogen changes when dilute hydrochloric acid with a higher concentration is used.[2]
4. (c)The student repeats the experiment at 30°C. All other conditions stay the same. Describe and explain, using collision theory, how the rate of reaction differs when a temperature of 30°C is used.[2]
5. (d)A sample of hydrogen is put into a gas syringe. The end of the gas syringe is then blocked so that no gas can escape. Explain, using kinetic particle theory, why decreasing the pressure in the gas syringe increases the volume of gas when the temperature stays the same.[1]

This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.