Question

Which of the following system is correct?

• A. For any cyclic process, $\Delta U=0$
• B. $(\frac{\delta U}{\delta V}{)}_T=\frac{a}{V^2}$ for 1 mole of a gas obeying van der waal's equation
• C. $\overline{C_p}=\infty$ for water when it is in equilibrium with vapour at $1atm$ pressure and $373K$
• D. For any real gas, the molar internal energy can be given as $\frac{3}{2}R$

Answer 1

Answer: (A), (B), (C)

$\overline{C_p}=\infty$ for water when it is in equilibrium with vapour at $1atm$ pressure and $373K$

(A) As $U$ is a state function, for any cyclic process, $\Delta U=0$
(B) $(\frac{\Delta U}{\Delta V}{)}_T=\frac{a}{V^2}$

$\frac{a}{V^2}$ is known as the internal pressure of the gas.

(C) During phase transition, T is constant, $dT=0,\overline{C_P}=(\frac{\delta H}{\delta T}{)}_P=\infty$
(D) Total molar kinetic energy =$\frac{3}{2}R$
$\text{Internal energy= Total kinetic energy + Potential energy}$