Anhydrous copper(II) sulfate, CuSO4\text{CuSO}_4CuSO4, can absorb water to form the hydrated salt CuSO4⋅5H2O\text{CuSO}_4\cdot 5\text{H}_2\text{O}CuSO4⋅5H2O.
CuSO4(s)+5H2O(l)→CuSO4⋅5H2O(s) \text{CuSO}_4(\text{s}) + 5\text{H}_2\text{O}(\text{l}) \rightarrow \text{CuSO}_4\cdot 5\text{H}_2\text{O}(\text{s}) CuSO4(s)+5H2O(l)→CuSO4⋅5H2O(s)Suggest one reason why the enthalpy change for this reaction cannot be determined directly by calorimetry.
Some enthalpies of solution are shown in the table below:
| Salt | Enthalpy of solution / kJ mol−1\text{kJ mol}^{-1}kJ mol−1 |
|---|---|
| CuSO4(s)\text{CuSO}_4(\text{s})CuSO4(s) | −66.2-66.2−66.2 |
| CuSO4⋅5H2O(s)\text{CuSO}_4\cdot 5\text{H}_2\text{O}(\text{s})CuSO4⋅5H2O(s) | +11.3+11.3+11.3 |
Calculate the enthalpy change for the absorption of water by CuSO4(s)\text{CuSO}_4(\text{s})CuSO4(s) to form CuSO4⋅5H2O(s)\text{CuSO}_4\cdot 5\text{H}_2\text{O}(\text{s})CuSO4⋅5H2O(s).
34 exam-style questions on AQA A Level Chemistry Energetics, covering Enthalpy change, Calorimetry, Applications of Hess's law, and Bond enthalpies. Each one has a worked solution and a mark scheme showing where the marks go.