As an isolated box, equally partitioned, contains two ideal gasses A and B as shown:

 

When the partition is removed, the gases mix. The changes in enthalpy $(∆\mathrm{H})$ and entropy $(∆\mathrm{S})$ in the process, respectively, are

1. Zero, positive

2. Zero, negative

3. Positive, zero

4. Negative, zero

The enthalpy of vaporization of a liquid is 20 kJ mol⁻¹. Assuming ideal behaviour, calculate the change in internal energy when 1 mol of the liquid vaporizes at 60°C and 1 bar.

An ideal gas expands isothermally at 300 K from a volume of 10⁻³ m³ to 10⁻² m³ against a constant
external pressure of 10⁵ N m⁻². Calculate the work associated with this expansion using the chemistry sign convention.

$∆{\mathrm{H}}_{\mathrm{f}}^0$ (298K) of methanol is given by the chemical equation:

1. \(\mathrm{C}(\text { diamond })+\frac{1}{2} \mathrm{O}_{2(\mathrm{~g})}+2 \mathrm{H}_{2(\mathrm{~g})} \rightarrow \mathrm{CH}_3 \mathrm{OH}_{(\mathrm{l})}\)

2. \(\mathrm{CH}_{4(\mathrm{~g})}+\frac{1}{2} \mathrm{O}_{2(\mathrm{~g})} \rightarrow \mathrm{CH}_3 \mathrm{OH}_{(\mathrm{g})}\)

3. \(\mathrm{CO}_{(\mathrm{g})}+2 \mathrm{H}_{2(\mathrm{~g})} \rightarrow \mathrm{CH}_3 \mathrm{OH}_{(\mathrm{l})}\)

4. \(\mathrm{C}(\text { graphite })+\frac{1}{2} \mathrm{O}_{2(\mathrm{~g})}+2 \mathrm{H}_{2(\mathrm{~g})} \rightarrow \mathrm{CH}_3 \mathrm{OH}_{(\mathrm{l})}\)

On complete combustion, 4.8 g of diamond releases 158.4 kJ of heat. The standard enthalpy of formation of gaseous carbon is 725 kJ mol⁻¹. Calculate the energy required for the following process:
(Given - Heat of combustion of graphite is −394 kJ mol⁻¹.)

(i) $\mathrm{C}\left(\mathrm{graphite}\right)\to \mathrm{C}\left(\mathrm{gas}\right)$

(ii) $\mathrm{C}\left(\mathrm{diamond}\right)\to \mathrm{C}\left(\mathrm{gas}\right)$

A piston filled with 0.04 mol of an ideal gas expands reversibly from 50.0 mL to 375 mL at a constant temperature of 37.0ºC. As it does so, it absorbs 208 J of heat. The values of q and w for the process will be-
(R = 8.314 J/mol K) (ln 7.5 = 2.01)

The standard enthalpy of combustion at ${25}^{\circ }C$ of hydrogen, cyclohexene (C₆H₁₀), and cyclohexane (C₆H₁₂) are -241, -3800 and -3920 kJ mol^-1, respectively. Calculate the standard enthalpy of hydrogenation of cyclohexene.

An ideal gas is expanded irreversibly against 10 bar pressure from 20 litres to 30 litres. Calculate 'w' if the process is isoenthalpic.

Entropy decreases during:

1. Crystallization of sucrose from solution

2. Rusting of iron

3. Melting of ice

4. Vaporization of camphor

At a temperature of 300K, what is the entropy change for the reaction given below?

2H₂ (g) + O₂ (g) $\to$2H₂O(l)

Standard entropies of H₂ (g), O₂(g) and H₂O(l) are 126.6, 201.20 and 68.0 JK^-1mol^-1 respectively.

1. -318.4 JK^-1mol^-1                           

2. 318.4 JK^-1mol^-1 

3. 31.84 JK^-1mol^-1                             

4. None of the above