Question

At atmospheric pressure, 1 g of water has a volume of 1671 cm³ in vapor phase. The change in internal energy when 1 g of water changes from liquid to vapor phase at atmospheric pressure is

• A. 2256 J
• B. 167 J
• C. 2423 J
• D. 2089 J

Hint:

For phase change problems, the change in internal energy is equal to the latent heat times the mass of the substance.

Answer 1

The Correct Option is A

The latent heat of vaporization of water is given as \( 2256 \times 10^3 \, \text{J/kg} \). To find the internal energy change for 1 g of water: \[ Q = 2256 \times 10^3 \times \frac{1}{1000} = 2256 \, \text{J} \]
Thus, the change in internal energy is 2256 J.