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Q. No.Calculate the standard enthalpy of formation (\(\Delta_fH^\circ\)) for 2 moles of liquid benzene (\(\mathrm{{C_6H_6}_{(l)}}\)) at 25°C, based on the given thermodynamic data.
Given Data:
\(\Delta _c\mathrm H\mathrm{(C_6H_6}_\mathrm{(l)})~= -3264.6~ \mathrm{~kJ} / \mathrm{mol}\)
\(\Delta _c\mathrm H\mathrm{(C}_\mathrm{(s)})~= -393.5~ \mathrm{~kJ} / \mathrm{mol}\)
\(\Delta _f\mathrm H\mathrm{(H_2O}_\mathrm{(l)})~= -285.83~ \mathrm{~kJ} / \mathrm{mol}\)
1. \(-~92.22 \mathrm{~kJ} / \mathrm{mol}\)
2. \(-46.11 \mathrm{~kJ} / \mathrm{mol}\)
3. \(+~92.22 \mathrm{~kJ} / \mathrm{mol}\)
4. \(+46.11 \mathrm{~kJ} / \mathrm{mol}\)
Subtopic: Thermochemistry |
Level 3: 35%-60%
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When solid sodium hydroxide, \(\mathrm{NaOH}(\mathrm{s})\), is added to water at \(25^{\circ} \mathrm{C}\), it dissolves and the temperature of the solution increases. Which of the following is true for the values of \(\Delta H\) and \(\Delta S\) for the dissolving process?
| \(\Delta H\) | \(\Delta S\) | |
| 1. | + | + |
| 2. | + | - |
| 3. | - | - |
| 4. | - | + |
Subtopic: Spontaneity & Entropy |
61%
Level 2: 60%+
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At a pressure of \(5 \times 10^5\) bar, the densities of diamond and graphite are 3 g/cc and 2 g/cc, respectively, at a certain temperature T. The value of \(\Delta U-\Delta H \mathrm{}\) for the conversion of 1 mole of graphite to 1 mole of diamond at a temperature T is:
1. \(100 \mathrm{~kJ} / \mathrm{mol}\)
2. \(50 \mathrm{~kJ} / \mathrm{mol}\)
3. \(-~100 \mathrm{~kJ} / \mathrm{mol}\)
4. \(-~50 \mathrm{~kJ} / \mathrm{mol}\)
1. \(100 \mathrm{~kJ} / \mathrm{mol}\)
2. \(50 \mathrm{~kJ} / \mathrm{mol}\)
3. \(-~100 \mathrm{~kJ} / \mathrm{mol}\)
4. \(-~50 \mathrm{~kJ} / \mathrm{mol}\)
Subtopic: Thermodynamics' Properties and process | Thermochemistry |
Level 3: 35%-60%
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For the process
\(\mathrm{H}_2 \mathrm{O}(\mathrm{l})(1 \mathrm{bar}, 373 \mathrm{~K}) \rightarrow \mathrm{H}_2 \mathrm{O}(\mathrm{g}) (1 \mathrm{bar}, 373 \mathrm{~K})\) , the correct set of thermodynamic parameters is:
1. \( \Delta G=+\mathrm{ve}, \Delta S=0\)
2. \(\Delta G=0, \Delta S=-\mathrm{ve}\)
3. \( \Delta G=0, \Delta S=+\mathrm{ve} \)
4. \( \Delta G=-\mathrm{ve}, \Delta S=+\mathrm{ve} \)
\(\mathrm{H}_2 \mathrm{O}(\mathrm{l})(1 \mathrm{bar}, 373 \mathrm{~K}) \rightarrow \mathrm{H}_2 \mathrm{O}(\mathrm{g}) (1 \mathrm{bar}, 373 \mathrm{~K})\) , the correct set of thermodynamic parameters is:
1. \( \Delta G=+\mathrm{ve}, \Delta S=0\)
2. \(\Delta G=0, \Delta S=-\mathrm{ve}\)
3. \( \Delta G=0, \Delta S=+\mathrm{ve} \)
4. \( \Delta G=-\mathrm{ve}, \Delta S=+\mathrm{ve} \)
Subtopic: Gibbs Energy Change |
Level 3: 35%-60%
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An ideal gas in a thermally insulated vessel at internal pressure = \(P_1,\) volume = \(V_1,\) and absolute temperature = \(T_1\) expands irreversibly against zero external pressure, as shown in the diagram. The final internal pressure, volume, and absolute temperature of the gas are \(P_2\), \(V_2\) and \(T_2\), respectively.
(b) \( T_2=T_1 \)
(c) \( P_2 V_2=P_1 V_1\)
(d) \(P_2 V_2^\gamma=P_1 V_1^\gamma \)
1. (a), (b) and (c)
2. (b) and (d)
3. (a) and (d)
4. None of the above
Which of the following relation(s) are correct for this expansion?
(a) \(q=0 \)(b) \( T_2=T_1 \)
(c) \( P_2 V_2=P_1 V_1\)
(d) \(P_2 V_2^\gamma=P_1 V_1^\gamma \)
1. (a), (b) and (c)
2. (b) and (d)
3. (a) and (d)
4. None of the above
Subtopic: Thermodynamics' Properties and process |
Level 3: 35%-60%
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Maximum work is obtained by a system in:
| 1. | Irreversible process | 2. | Reversible process |
| 3. | Adiabatic process | 4. | Isobaric process |
Subtopic: First Law of Thermodynamics |
Level 3: 35%-60%
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For an isolated system, if ΔU=0, then what is the value of ΔS?
| 1. | ΔS=0 | 2. | ΔS > 0 |
| 3. | ΔS < 0 | 4. | ΔS is not defined |
Subtopic: Spontaneity & Entropy |
Level 3: 35%-60%
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What is the entropy change (\(\Delta S\)) for water at its boiling point of 100°C, expressed in cal K⁻¹ mol⁻¹?
[For water \(\Delta H_{vap} = 540 ~cal~ g^{-1} \) ]
1. 540
2. 1.45
3. 26.06
4. 35.60
[For water \(\Delta H_{vap} = 540 ~cal~ g^{-1} \) ]
1. 540
2. 1.45
3. 26.06
4. 35.60
Subtopic: Spontaneity & Entropy |
Level 3: 35%-60%
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C2H6(g) + \(\frac{7}{2}\)O2(g) → 2CO2(g) + 3H2O(g) ∆H˚ = –1427.7 kJ
If the enthalpy of vaporization for H2O(l) is 44.0 kJ/mol, Calculate ∆H˚ for this reaction if H2O(l) is formed instead of H2O(g).
1. –1295.7 kJ
2. –1383.7 kJ
3. –1471.7 kJ
4. –1559.7 kJ
If the enthalpy of vaporization for H2O(l) is 44.0 kJ/mol, Calculate ∆H˚ for this reaction if H2O(l) is formed instead of H2O(g).
1. –1295.7 kJ
2. –1383.7 kJ
3. –1471.7 kJ
4. –1559.7 kJ
Subtopic: Hess's Law |
Level 3: 35%-60%
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The enthalpy of combustion of four allotropic forms of element 'X' are given as:
The most stable allotropic form of element 'X' is:
1. A
2. B
3. C
4. D
| Allotropic forms | \(\Delta_\text{comb}H^\circ\)(kJ/mol) |
| A. | -270.3 |
| B. | -189.1 |
| C. | -390.5 |
| D. | -465.0 |
1. A
2. B
3. C
4. D
Subtopic: Thermochemistry |
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