Q. No.What is the change in internal energy for 5 moles of an ideal gas when it undergoes reversible compression from 100 K to 200 K?
[Given CV = 28 J K–1 mol–1]
| 1. | ΔU = 8kJ | 2. | ΔU = 14kJ |
| 3. | ΔU = 10kJ | 4. | ΔU = 2.8 kJ |
1. \(\mathrm{PCl}_5(\mathrm{~g}) \rightarrow \mathrm{PCl}_3(\mathrm{~g})+\mathrm{Cl}_2(\mathrm{~g})\)
2. \(2 \mathrm{CO}(\mathrm{g})+\mathrm{O}_2(\mathrm{~g}) \rightarrow 2 \mathrm{CO}_2(\mathrm{~g})\)
3. \(\text 3\mathrm{N}_2(\mathrm{~g})+3 \mathrm{H}_2(\mathrm{~g}) \rightarrow 2 \mathrm{NH}_3(\mathrm{~g})\)
4. \(\mathrm{H}_2(\mathrm{~g})+\mathrm{I}_2(\mathrm{~g}) \rightarrow 2 \mathrm{HI}(\mathrm{g})\)
| (i) | \(\mathrm{H}_2(\mathrm{~g})+\frac{1}{2} \mathrm{O}_2(\mathrm{~g}) \rightarrow \mathrm{H}_2 \mathrm{O}(\mathrm{l})\) \(\Delta \mathrm{H}^{\circ}{ }_{298 \mathrm{~K}}=-285.9 \mathrm{~kJ} \mathrm{~mol}^{-1}\) |
| (ii) | \( \mathrm{H}_2(\mathrm{~g})+\frac{1}{2} \mathrm{O}_2(\mathrm{~g}) \rightarrow \mathrm{H}_2 \mathrm{O}(\mathrm{~g}) \) \( \Delta \mathrm{H}^{\circ}{ }_{298 \mathrm{~K}}=-241.8 \mathrm{~kJ} \mathrm{~mol}^{-1}\) |
1. \(\mathrm{74.8~kJ} \mathrm{mol}^{-1}\)
2. \(\mathrm{22.0~kJ} \mathrm{mol}^{-1}\)
3. \(\mathrm{44.1~kJ} \mathrm{mol}^{-1}\)
4. \(\mathrm{52.7kJ} \mathrm{mol}^{-1}\)
A 1.0 mol sample of a monoatomic ideal gas undergoes a complete cyclic process involving expansion and compression, as illustrated in the accompanying graph. What is the value of the change in enthalpy (\(\Delta H\)) for the entire cycle?
1. +0.05 J
2. - 0.05 J
3. 0 J
4. +1 J
| 1. | In a reversible process, the system and surroundings are always in equilibrium with each other. |
| 2. | Work done in free expansion > 0. |
| 3. | For adiabatic change, \(\Delta q \) = 0 . |
| 4. | For a process carried at constant pressure, \(\Delta H = q_p \) |
For the reaction,
C2H5OH(l) + 3O2(g) →2CO2(g) + 3H2O(l)
which one is true?
| 1. | ∆H = ∆E – RT | 2. | ∆H = ∆E + RT |
| 3. | ∆H = ∆E + 2RT | 4. | ∆H = ∆E – 2RT |
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Five moles of an ideal gas at 1 bar and 298 K undergo free expansion (expansion into vacuum) such that its volume becomes double. Calculate the work done during the process:
2. \( \text {-RT }\left(\mathrm{V}_2-\mathrm{V}_1\right) \)
3. \( \text {-RT } \ln \mathrm({V}_1 / \mathrm{V}_2 )\)
4. Zero
Nitrogen gas (N₂) is confined in a cylinder fitted with a movable piston and undergoes an adiabatic expansion.
Which of the following statements is correct for this process?
1. q=w
2. ∆U=w
3. ∆U=0
4. ∆U=q
1. \( \mathrm{H}_2(\mathrm{~g})+\mathrm{Cl}_2(\mathrm{~g}) \longrightarrow 2 \mathrm{HCl}(\mathrm{g}) \)
2. \(\mathrm{PCl}_5 (g) \longrightarrow \mathrm{PCl}_3(\mathrm{~g})+\mathrm{Cl}_2(\mathrm{~g}) \)
3. \( \mathrm{N}_2 \mathrm{O}_4(\mathrm{~g}) \longrightarrow 2 \mathrm{NO}_2(\mathrm{~g}) \)
4. \(\mathrm{NH}_4 \mathrm{HS}(\mathrm{s}) \longrightarrow \mathrm{NH}_3(\mathrm{~g})+\mathrm{H}_2 \mathrm{~S}(\mathrm{~g})\)
\(3{CaO}+2{Al} \longrightarrow 3{Ca}+{Al}_2 \mathrm{O}_3\)
The standard enthalpies of formation of \(Al_2O_3~ \text{and}~ CaO~ \text{are}~ –1675 ~kJ~ mol^{–1}\) and \(–635~ kJ ~mol^{–1}\) respectively.
Calculate the standard reaction enthalpy (\(\Delta_ rH^0\)) for this reaction:
1. \(1230 ~\mathrm{kJ} \)
2. \(43 ~ \mathrm{kJ} \)
3. \(230~ \mathrm{kJ} \)
4. \(312~ \mathrm{kJ} \)
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