Thermodynamics - Physical Chemistry - Chemistry Previous Year Questions

One mole of an ideal gas at 300 K and 20 atm expands to 2 atm under isothermal and reversible conditions. The work done by the gas is $-x \mathrm{~kJ} \mathrm{~mol}^{-1}$. The value of $x$ is $\left(R=8.3 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}\right)$

At 298 K , the enthalpy change ( in kJ ) for the reaction given below is

$$\mathrm{CH}_4(g)+\mathrm{O}_2(g) \longrightarrow \mathrm{C}(s)+2 \mathrm{H}_2 \mathrm{O}(l)$$

$$\begin{aligned} Given:\mathrm{H}_2(g)+\frac{1}{2} \mathrm{O}_2(g) & \longrightarrow \mathrm{H}_2 \mathrm{O}(l) ; \Delta H^{\ominus}=-286 \mathrm{~kJ} \\ \mathrm{C}(s)+\mathrm{O}_2(g) & \longrightarrow \mathrm{CO}_2(g) ; \Delta H^{\ominus}=-394 \mathrm{~kJ} \\ \mathrm{CH}_4(g)+2 \mathrm{O}_2(g) & \longrightarrow \mathrm{CO}_2(g)+2 \mathrm{H}_2 \mathrm{O}(l) \Delta H^{\ominus}=-890 \mathrm{~kJ}\end{aligned}$$

Which of the following processes are reversible?

I. Vaporisation of a liquid at its boiling point.

II. Expansion of gas into vacuum.

III. Transformation of a solid substance into liquid at its melting point.

At 298 K , if the standard Gibbs energy change $\Delta_r G^{\circ}$ of a reaction is -115 kJ , the value of $\log _{10} K_p$ will be $\left(R=8.314 \mathrm{JK}^{-1} \mathrm{~mol}^{-1}\right)$

The $C_p$ of an ideal gas is $10314 \mathrm{Jmol}^{-1} \mathrm{~K}^{-1}$. One mole of this gas is expanded against a constant pressure of $p \mathrm{~atm}$. The change in temperature during expansion is 1.0 K . The value of $q$ (in J ) and $\Delta H$ (in $\mathrm{Jmol}^{-1}$ ) are respectively.

The entropy and enthalpy changes for the reaction $\mathrm{CO}(\mathrm{g})+\mathrm{H}_2 \mathrm{O}(\mathrm{g}) \rightleftharpoons \mathrm{CO}_2(\mathrm{~g})+\mathrm{H}_2(\mathrm{~g})$ at 300 K and 1 atm are respectively $-42.4 \mathrm{JK}^{-1}$ and -41.2 kJ . The temperature at which the reaction will go in the reverse direction is