Question

Latent heat of vaporization of liquid at $500K$ and $1$ atm pressure is $10kcal/mol$. What is the change in internal energy when $3$ moles of the liquid is vaporized at the same temperature?

• A. $27kcal$
• B. $7kcal$
• C. $33kcal$
• D. $25kcal$

Answer 1

The correct option is A $27kcal$

Molar enthalpy of vaporization is the amount of energy needed to change one mole of a substance from the liquid phase to the gas phase at constant temperature and pressure.

According to question.

$\Delta n_g=3$

$\Delta E$ $=$ $\Delta H-\Delta n_{g}RT$

$=3\times 10-3\times 500\times 0.002$

$\Delta E=27kcal$