The enthalpies of solution for copper sulphate pentahydrate and anhydrous copper sulphate are respectively 11.7 and `-65.5 kJ mol^(-1)`.The hydration enthalpy of anhydrous copper sulphate is

Options

A. `53.8 kJ "mol"^(-1)`
B. `-9.8 kJ "mol"^(-1)`
C. `-77.2 kJ "mol"^(-1)`
D. `-53.8 kJ " mol^(-1)`

Explanation

To find the hydration enthalpy of anhydrous copper sulfate (CuSO4), we can use the given enthalpies of solution for both copper sulfate pentahydrate (CuSO4·5H2O) and anhydrous copper sulfate (CuSO4).

### Step-by-Step Solution:

1. **Identify the Given Data:**
- Enthalpy of solution for copper sulfate pentahydrate (CuSO4·5H2O), ΔH1 = +11.7 kJ/mol
- Enthalpy of solution for anhydrous copper sulfate (CuSO4), ΔH2 = -65.5 kJ/mol

2. **Understand the Relationship:**
- The hydration enthalpy of anhydrous copper sulfate (ΔH3) can be derived from the enthalpies of solution using the following relationship:
\[ \Delta H_3 = \Delta H_2 - \Delta H_1 \]
- Here, ΔH3 is the enthalpy change when anhydrous copper sulfate is hydrated to form copper sulfate pentahydrate.

3. **Substitute the Values:**
- Substitute the values of ΔH1 and ΔH2 into the equation:
\[ \Delta H_3 = (-65.5 \text{ kJ/mol}) - (11.7 \text{ kJ/mol}) \]

4. **Calculate ΔH3:**
- Perform the calculation:
\[ \Delta H_3 = -65.5 - 11.7 = -77.2 \text{ kJ/mol} \]

5. **Conclusion:**
- The hydration enthalpy of anhydrous copper sulfate is:
\[ \Delta H_3 = -77.2 \text{ kJ/mol} \]

### Final Answer:
The hydration enthalpy of anhydrous copper sulfate is **-77.2 kJ/mol**.