Question

Calculate the internal energy change when 2 moles of water at 0 degrees converts into ice at 0-degree centigrade?

• A. 12 KJ per mole
• B. 6 KJ per mole
• C. 1 KJ per mole
• D. 102 KJ per mole

Hint:

The internal energy change during a phase transition like freezing is given by the latent heat of fusion, which is negative when energy is released.

Answer 1

The Correct Option is B

Step 1: Understand the phase change.
The process of freezing water to form ice at 0°C involves a latent heat of fusion.
The latent heat of fusion of water is approximately 6 KJ/mol.
Step 2: Apply the latent heat of fusion.
Since we are converting 2 moles of water into ice, the total energy change will be \( 6 \, \text{KJ/mol} \times 2 \, \text{mol} = 12 \, \text{KJ} \).
However, since this is the energy released during freezing, the internal energy change is negative: \( -6 \, \text{KJ/mol} \).