90 g of water spilled out from a vessel in the room on the floor. Assuming that water vapour behaving as an ideal gas, calculate the internal energy change when the spilled water undergoes complete evaporation at `100^(@)C`. (Given the molar enthalpy of vaporisation of water at 1 bar and 373 K = 41 kJ `mol^(-1)`).

Explanation

To solve the problem of calculating the internal energy change when 90 g of water evaporates at 100°C, we can follow these steps:

### Step 1: Convert the mass of water to moles
To find the number of moles of water, we use the formula:
\[ \text{Number of moles} (n) = \frac{\text{mass (g)}}{\text{molar mass (g/mol)}} \]
The molar mass of water (H₂O) is approximately 18 g/mol.
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