A-LevelChemistryChemical energeticsFeb/Mar 2021Paper 5 Q110 Marks
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
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