Zinc metal reacts with aqueous copper(II) sulfate. Zn(s) + CuSO₄(aq) → Cu(s) + ZnSO₄(aq) The enthalpy change of this reaction, ΔΗ, can be determined by adding excess zinc powder to a measured volume of 0.500 mol dm⁻³ aqueous copper(II) sulfate. The temperature of 25.0 cm³ of 0.500 mol dm⁻³ aqueous copper(II) sulfate is recorded for three minutes. At four minutes 3 g, an excess, of zinc powder is added and the mixture is continuously stirred. The temperature is recorded at times shown in the table. time/min | 0 | 1 | 2 | 3 | 4½ | 5 | 5½ | 6 | 6½ | 7 | 8 | 9 | 10 temperature /°C | 18 | 19.5 | 19.5 | 19.5 | 32.5 | 38 | 36 | 34 | 33 | 32.5 | 31.5 | 31 | 31

1. (a)Use the results table to deduce the graduations on the thermometer that is used to record these temperature readings.[1]
2. (b)Draw a labelled diagram of the apparatus set up at one minute.[2]
3. (c)Plot a graph of temperature (y-axis) against time (x-axis). Use a cross (x) to plot each data point. Draw a line of best fit during cooling. Extrapolate the cooling curve back to four minutes and determine the temperature change during the reaction. temperature change = ................................... °C[2]
4. (d)Use the formula ∆H = –mc∆T to determine the enthalpy change of reaction, ΔH, in kJ mol⁻¹. Assume: mass of 1.00 cm³ of solution = 1.00g c = 4.18 J g⁻¹ K⁻¹. ΔΗ = ................................... kJ mol⁻¹[2]
5. (e)(i)The mass of zinc is doubled. effect on heat loss .................................................................................................................................... explanation ....................................................................................................................................[1]
6. (e)(ii)The concentration of 25.0 cm³ of aqueous copper(II) sulfate is doubled. The amount of zinc used is still an excess. effect on heat loss .................................................................................................................................... explanation ....................................................................................................................................[1]
7. (e)(iii)The volume of 0.500 mol dm⁻³ aqueous copper(II) sulfate is doubled. The amount of zinc used is still an excess. effect on heat loss .................................................................................................................................... explanation ....................................................................................................................................[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.