A student investigates the rate of reaction when zinc reacts with dilute hydrochloric acid, HCl(aq). Zn(s) + 2HCl(aq) → ZnCl₂(aq) + H₂(g) The student uses the following method. Step 1 Accurately weigh 1.00 g of zinc foil. Step 2 Add 50 cm³ of 2.00 moldm⁻³ HCl(aq) to a conical flask. Step 3 Add the zinc foil to the 50cm³ of HCl(aq) in the flask and immediately start a timer. Step 4 Stop the timer when 20.0cm³ of H₂(g) has been collected. Step 5 Repeat Steps 1 to 4 using lower concentrations of HCl(aq).

1. (a)Complete [Figure 2.1] to show the apparatus that the student can use to collect and measure the volume of hydrogen produced. Label your diagram.[3]
2. (b)The student wants to perform a similar experiment using 0.100 moldm⁻³ HCl(aq). Describe how the student should make a standard solution of 250.0 cm³ of 0.100 moldm⁻³ HCl(aq) starting from a solution of 2.00moldm⁻³ HCl(aq). Give the name and size of any key apparatus which should be used and describe how the student should ensure the volume is exactly 250.0 cm³. Write your answer using a series of numbered steps.[3]
3. (c)(i)The student wears chemically resistant gloves when using 6.00moldm⁻³ HCl(aq). Suggest why.[1]
4. (c)(ii)The student obtains the results shown in Table 2.1. In these experiments 1/t can be considered to be proportional to the initial rate of reaction. Complete the table by calculating 1/t for each concentration. Give your answers to three significant figures.[1]
5. (c)(iii)Use your data from Table 2.1 to produce a sketch graph of 1/t against concentration in [Figure 2.2]. It is not necessary to include a scale on the axes. Label the sketched line 'A'.[1]
6. (c)(iv)On [Figure 2.2] sketch a second line to show the graph of concentration against 1/t if powdered zinc is used in the experiment instead of zinc foil. Label this line 'B'.[1]
7. (c)(v)Using your data in Table 2.1, deduce the rate equation for the reaction between Zn(s) and HCl(aq). rate =[1]
8. (d)(i)At higher concentrations than those shown in Table 2.1, significant temperature increases occur. Suggest how line 'A' in [Figure 2.2] would be different at these higher concentrations. Explain your answer.[2]
9. (d)(ii)Suggest one way in which the temperature increase may be minimised.[1]
10. (e)(i)The zinc foil has an oxide layer. Suggest how the oxide layer can be removed before weighing the zinc foil.[1]
11. (e)(ii)If the student does not remove the oxide layer, the initial rate of reaction is lower than it should be. Explain why the initial rate of reaction is lower than it should be.[1]

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