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Q. No.Burning 48.0 g of graphite in excess oxygen under standard conditions releases 1574.0 kJ of heat. What is \(\Delta H_f^{\circ}\) of CO2(g)?
1. 157 kJ mol-1
2. –1574 kJ mol-1
3. –394 kJ mol-1
4. 32.8 kJ mol-1
1. 157 kJ mol-1
2. –1574 kJ mol-1
3. –394 kJ mol-1
4. 32.8 kJ mol-1
Subtopic: Thermochemistry |
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Which reaction has ΔH∘reaction equal to the \(\Delta H_f^{\circ}\) of CaSO3(s)?
1. Ca(s) + \(\frac{1}{8}\) S8(s, rhombic) + \(\frac{3}{2}\) O2(g) → CaSO3(s)
2. 8Ca(s) + S8(s) + 12O2(g) → 8CaSO3(s)
3. 8Ca(s) + S8(g) + 12O2(g) → 8CaSO3(s)
4. CaO(s) + SO2(g) → CaSO3(s)
1. Ca(s) + \(\frac{1}{8}\) S8(s, rhombic) + \(\frac{3}{2}\) O2(g) → CaSO3(s)
2. 8Ca(s) + S8(s) + 12O2(g) → 8CaSO3(s)
3. 8Ca(s) + S8(g) + 12O2(g) → 8CaSO3(s)
4. CaO(s) + SO2(g) → CaSO3(s)
Subtopic: Thermochemistry |
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Calculate the Gibbs energy change when 1 mole of NaCl is dissolved in water at 298 K. Given,
a. Lattice energy of NaCl = 778 kJ mol-1
b. Hydration energy of NaCl =-774.3 kJ mol-1
c. Entropy change at 298 K = 43 JK-1 mol-1
| 1. | -3.7 kJ | 2. | -9.1 kJ |
| 3. | -43 kJ | 4. | -13.14 kJ |
Subtopic: Thermochemistry |
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The standard enthalpies of the formation of NO2(g) and N2O4(g) are 8 kcal mol–1 and 2 kcal mol–1 respectively. The heat of dimerization of NO2 in the gaseous state is:
| 1. | 10 k cal mol–1 | 2. | 6.0 k cal mol–1 |
| 3. | –14 k cal mol–1 | 4. | –6.0 k cal mol–1 |
Subtopic: Thermochemistry |
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If bond enthalpies of \(C-C,C-H,O=O,C=O \) and \(O-H \) are
a, b, c, d, and e respectively, then the heat of combustion of ethane will be:
1. \(6 b+\frac{7}{2} c+a-2 d-3e \)
2. \(b+c+a-4 d-3e \)
3. \(6 b+\frac{7}{2} c+a-4 d-6e \)
4. \(6 b+7 c+a-4 d-6e \)
a, b, c, d, and e respectively, then the heat of combustion of ethane will be:
1. \(6 b+\frac{7}{2} c+a-2 d-3e \)
2. \(b+c+a-4 d-3e \)
3. \(6 b+\frac{7}{2} c+a-4 d-6e \)
4. \(6 b+7 c+a-4 d-6e \)
Subtopic: Thermochemistry |
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The average S–F bond energy in kJ mol–1 of SF6 is:
[The values of standard enthalpy of formation of
SF6(g), S(g), and F(g) are –1100, 275, and 80 kJmol–1 respectively.]
| 1. | 309 kJ mol–1 | 2. | 313 kJ mol–1 |
| 3. | 305 kJ mol–1 | 4. | 318 kJ mol–1 |
Subtopic: Thermochemistry |
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