If the heat fo dissolution of anhydrous `CuSO_(4)` and `CuSO_(4).5H_(2)O` is `-15.89 kcal` and `2.80 kcal`, respectively, then the heat of hydration fo `CuSO_(4)` to form `CuSO_(4).5H_(2)O` is

Options

A. `-13.09 kcal`
B. `-18.69 kcal`
C. `+13.09 kcal`
D. `+18.69kcal`

Explanation

To find the heat of hydration of anhydrous CuSO₄ to form CuSO₄·5H₂O, we can use the given heats of dissolution for both compounds.

### Step-by-Step Solution:

1. **Identify the Given Values:**
- Heat of dissolution of anhydrous CuSO₄ (ΔH₁) = -15.89 kcal
- Heat of dissolution of CuSO₄·5H₂O (ΔH₂) = -2.80 kcal

2. **Set Up the Reaction:**
The heat of hydration (ΔH_hydration) can be expressed as:
\[ \text{CuSO}_4 (s) + 5 \text{H}_2\text{O} (l) \rightarrow \text{CuSO}_4 \cdot 5\text{H}_2\text{O} (s) \]

3. **Use the Formula for Heat of Hydration:**
The heat of hydration can be calculated using the following relationship:
\[ \Delta H_{\text{hydration}} = \Delta H_1 - \Delta H_2 \]
where:
- ΔH₁ is the heat of dissolution of CuSO₄,
- ΔH₂ is the heat of dissolution of CuSO₄·5H₂O.

4. **Substitute the Values:**
\[ \Delta H_{\text{hydration}} = (-15.89 \text{ kcal}) - (-2.80 \text{ kcal}) \]

5. **Calculate the Result:**
\[ \Delta H_{\text{hydration}} = -15.89 + 2.80 = -18.69 \text{ kcal} \]

6. **Final Answer:**
The heat of hydration of CuSO₄ to form CuSO₄·5H₂O is -18.69 kcal.