Assuming the water vapour to be a perfect gas, calculate the internal energy change when 1 mol of water at `100^(@)C` and 1 bar pressure is converted to ice at `0^(@)C`. Given the enthalpy of fusion of ice is 6.00 kJ `"mol"^(- 1)` heat capacity of water is `4.2 J//g^(@)C`
The change take place as follows:

Explanation

To calculate the internal energy change when 1 mole of water at 100°C and 1 bar pressure is converted to ice at 0°C, we will follow these steps:

### Step 1: Calculate the heat required to cool water from 100°C to 0°C

We will use the formula:
\[ q = m \cdot C \cdot \Delta T \]
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