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1 | ![](/olcweb/styles/shared/spacer.gif) | ![](/olcweb/styles/shared/spacer.gif) For which of the following reactions is ΔS expected to be positive? |
| ![](/olcweb/styles/shared/spacer.gif) | A)![](/olcweb/styles/shared/spacer.gif) | NH4Cl(s) →
NH3(g) + HCl(g) |
| ![](/olcweb/styles/shared/spacer.gif) | B)![](/olcweb/styles/shared/spacer.gif) | 2H(g) + O(g) →
H2O(g) |
| ![](/olcweb/styles/shared/spacer.gif) | C)![](/olcweb/styles/shared/spacer.gif) | HCl(g) + NaOH(s) →
NaCl(g) + H2O(g) |
| ![](/olcweb/styles/shared/spacer.gif) | D)![](/olcweb/styles/shared/spacer.gif) | 2H2(g) + O2(g) →
2H2O(g) |
| ![](/olcweb/styles/shared/spacer.gif) | E)![](/olcweb/styles/shared/spacer.gif) | N2(g) + 3H2(g) →
2NH3(g) |
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2 | ![](/olcweb/styles/shared/spacer.gif) | ![](/olcweb/styles/shared/spacer.gif) Which of the following changes, all involving one mole of pure water, has the greatest ΔSsys? |
| ![](/olcweb/styles/shared/spacer.gif) | A)![](/olcweb/styles/shared/spacer.gif) | raising the temperature of the solid from –10.0º
C to 0.0º
C |
| ![](/olcweb/styles/shared/spacer.gif) | B)![](/olcweb/styles/shared/spacer.gif) | melting the solid at 0º
C |
| ![](/olcweb/styles/shared/spacer.gif) | C)![](/olcweb/styles/shared/spacer.gif) | raising the temperature of the liquid from 0.0º
C to 10.0º
C |
| ![](/olcweb/styles/shared/spacer.gif) | D)![](/olcweb/styles/shared/spacer.gif) | vaporizing the liquid at 100.0º
C |
| ![](/olcweb/styles/shared/spacer.gif) | E)![](/olcweb/styles/shared/spacer.gif) | raising the temperature of the vapor 100.0º
C to 110.0º
C |
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3 | ![](/olcweb/styles/shared/spacer.gif) | ![](/olcweb/styles/shared/spacer.gif) Calculate ΔSº for the reaction
C9H20(l) + 14O2(g) →
9CO2(g) + 10H2O(g)
Data: Standard molar entropies, Sº in J/mol.K: C9H20(l), 393.7; O2(g), 205.0; CO2(g), 213.7; H2O(g), 188.7 |
| ![](/olcweb/styles/shared/spacer.gif) | A)![](/olcweb/styles/shared/spacer.gif) | -196.3 J/K |
| ![](/olcweb/styles/shared/spacer.gif) | B)![](/olcweb/styles/shared/spacer.gif) | +196.3 J/K |
| ![](/olcweb/styles/shared/spacer.gif) | C)![](/olcweb/styles/shared/spacer.gif) | -546.6 J/K |
| ![](/olcweb/styles/shared/spacer.gif) | D)![](/olcweb/styles/shared/spacer.gif) | +546.6 J/K |
| ![](/olcweb/styles/shared/spacer.gif) | E)![](/olcweb/styles/shared/spacer.gif) | +1341 J/K |
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4 | ![](/olcweb/styles/shared/spacer.gif) | ![](/olcweb/styles/shared/spacer.gif) Select the most likely standard entropy change, ΔS° for the reaction:
2H2(g) + O2(g) →
2H2O(g) |
| ![](/olcweb/styles/shared/spacer.gif) | A)![](/olcweb/styles/shared/spacer.gif) | 0 J/K |
| ![](/olcweb/styles/shared/spacer.gif) | B)![](/olcweb/styles/shared/spacer.gif) | 189 J/K |
| ![](/olcweb/styles/shared/spacer.gif) | C)![](/olcweb/styles/shared/spacer.gif) | -87 J/K |
| ![](/olcweb/styles/shared/spacer.gif) | D)![](/olcweb/styles/shared/spacer.gif) | +44 J/K |
| ![](/olcweb/styles/shared/spacer.gif) | E)![](/olcweb/styles/shared/spacer.gif) | –5 J/K |
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5 | ![](/olcweb/styles/shared/spacer.gif) | ![](/olcweb/styles/shared/spacer.gif) Which of the following statements about entropy and enthalpy of a system is correct? |
| ![](/olcweb/styles/shared/spacer.gif) | A)![](/olcweb/styles/shared/spacer.gif) | The absolute entropy of pure oxygen at 25º
C and 1 atm is zero. |
| ![](/olcweb/styles/shared/spacer.gif) | B)![](/olcweb/styles/shared/spacer.gif) | When ice melts, ΔS is positive and ΔH is negative. |
| ![](/olcweb/styles/shared/spacer.gif) | C)![](/olcweb/styles/shared/spacer.gif) | When a candle burns, ΔS is positive and ΔH is negative. |
| ![](/olcweb/styles/shared/spacer.gif) | D)![](/olcweb/styles/shared/spacer.gif) | The entropy of a system must increase for the reaction to be spontaneous. |
| ![](/olcweb/styles/shared/spacer.gif) | E)![](/olcweb/styles/shared/spacer.gif) | None of the above statements is correct. |
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6 | ![](/olcweb/styles/shared/spacer.gif) | ![](/olcweb/styles/shared/spacer.gif) Which of the following is necessary and sufficient for a process be spontaneous? |
| ![](/olcweb/styles/shared/spacer.gif) | A)![](/olcweb/styles/shared/spacer.gif) | ΔG < 0 |
| ![](/olcweb/styles/shared/spacer.gif) | B)![](/olcweb/styles/shared/spacer.gif) | ΔSsurr > 0 |
| ![](/olcweb/styles/shared/spacer.gif) | C)![](/olcweb/styles/shared/spacer.gif) | ΔH < 0 |
| ![](/olcweb/styles/shared/spacer.gif) | D)![](/olcweb/styles/shared/spacer.gif) | ΔSsys > 0 |
| ![](/olcweb/styles/shared/spacer.gif) | E)![](/olcweb/styles/shared/spacer.gif) | ΔH > TΔS
|
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7 | ![](/olcweb/styles/shared/spacer.gif) | ![](/olcweb/styles/shared/spacer.gif) Given the following reactions and their values of ΔG°:
2CO(g) + O2(g) →
2CO2(g) ΔG° = -516 kJ
4MnO(s) + O2(g) →
2Mn2O3(s) ΔG° = -312 kJ
Calculate ΔG° for the reaction:
Mn2O3(s) + CO(g) →
2MnO(s) + CO2(g) |
| ![](/olcweb/styles/shared/spacer.gif) | A)![](/olcweb/styles/shared/spacer.gif) | +204 kJ |
| ![](/olcweb/styles/shared/spacer.gif) | B)![](/olcweb/styles/shared/spacer.gif) | -204 kJ |
| ![](/olcweb/styles/shared/spacer.gif) | C)![](/olcweb/styles/shared/spacer.gif) | +102 kJ |
| ![](/olcweb/styles/shared/spacer.gif) | D)![](/olcweb/styles/shared/spacer.gif) | -102 kJ |
| ![](/olcweb/styles/shared/spacer.gif) | E)![](/olcweb/styles/shared/spacer.gif) | -414 kJ |
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8 | ![](/olcweb/styles/shared/spacer.gif) | ![](/olcweb/styles/shared/spacer.gif) Methanol is used as a high performance fuel. Calculate ΔG° for the combustion reaction:
2CH3OH(l) + 3O2(g) →
2CO2(g) + 4H2O(g)
Data: Standard free energies of formation, ΔG°f (kJ/mol): CH3OH(l), -163 kJ; O2(g), 0; CO2(g), -394; H2O(g), -229 |
| ![](/olcweb/styles/shared/spacer.gif) | A)![](/olcweb/styles/shared/spacer.gif) | +1146 kJ |
| ![](/olcweb/styles/shared/spacer.gif) | B)![](/olcweb/styles/shared/spacer.gif) | +1460 kJ |
| ![](/olcweb/styles/shared/spacer.gif) | C)![](/olcweb/styles/shared/spacer.gif) | -460 kJ |
| ![](/olcweb/styles/shared/spacer.gif) | D)![](/olcweb/styles/shared/spacer.gif) | -945 kJ |
| ![](/olcweb/styles/shared/spacer.gif) | E)![](/olcweb/styles/shared/spacer.gif) | -1378 kJ |
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9 | ![](/olcweb/styles/shared/spacer.gif) | ![](/olcweb/styles/shared/spacer.gif) Consider the reaction:
C9H20(l) + 14O2(g) →
9CO2(g) + 10H2O(g)
For this reaction, ΔSº is +546.6 J/K and ΔHº is -5685 kJ. Use these values to calculate ΔGº. |
| ![](/olcweb/styles/shared/spacer.gif) | A)![](/olcweb/styles/shared/spacer.gif) | +5848 kJ/mol |
| ![](/olcweb/styles/shared/spacer.gif) | B)![](/olcweb/styles/shared/spacer.gif) | -5848 kJ/mol |
| ![](/olcweb/styles/shared/spacer.gif) | C)![](/olcweb/styles/shared/spacer.gif) | +5139 kJ/mol |
| ![](/olcweb/styles/shared/spacer.gif) | D)![](/olcweb/styles/shared/spacer.gif) | -5139 kJ/mol |
| ![](/olcweb/styles/shared/spacer.gif) | E)![](/olcweb/styles/shared/spacer.gif) | +4922 kJ/mol |
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10 | ![](/olcweb/styles/shared/spacer.gif) | ![](/olcweb/styles/shared/spacer.gif) In 1774 Joseph Priestley prepared the element oxygen by heating mercury(II) oxide:
HgO(s) →
Hg(l) + ½O2(g)
For this reaction, ΔHº
= 90.84 kJ and ΔSº
= 108 J/K. Which of the following statements is true? |
| ![](/olcweb/styles/shared/spacer.gif) | A)![](/olcweb/styles/shared/spacer.gif) | The reaction is only spontaneous at low temperatures. |
| ![](/olcweb/styles/shared/spacer.gif) | B)![](/olcweb/styles/shared/spacer.gif) | The reaction is spontaneous at all temperatures. |
| ![](/olcweb/styles/shared/spacer.gif) | C)![](/olcweb/styles/shared/spacer.gif) | ΔGº
becomes less favorable as the temperature is raised. |
| ![](/olcweb/styles/shared/spacer.gif) | D)![](/olcweb/styles/shared/spacer.gif) | The reaction is spontaneous only at high temperatures. |
| ![](/olcweb/styles/shared/spacer.gif) | E)![](/olcweb/styles/shared/spacer.gif) | The reaction is spontaneous under standard conditions at 25°C. |
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11 | ![](/olcweb/styles/shared/spacer.gif) | ![](/olcweb/styles/shared/spacer.gif) Which of the following is true for an exothermic process? |
| ![](/olcweb/styles/shared/spacer.gif) | A)![](/olcweb/styles/shared/spacer.gif) | qsys > 0, ΔSsurr < 0 |
| ![](/olcweb/styles/shared/spacer.gif) | B)![](/olcweb/styles/shared/spacer.gif) | qsys < 0, ΔSsurr < 0 |
| ![](/olcweb/styles/shared/spacer.gif) | C)![](/olcweb/styles/shared/spacer.gif) | qsys < 0, ΔSsurr > 0 |
| ![](/olcweb/styles/shared/spacer.gif) | D)![](/olcweb/styles/shared/spacer.gif) | qsys > 0, ΔSsurr > 0 |
| ![](/olcweb/styles/shared/spacer.gif) | E)![](/olcweb/styles/shared/spacer.gif) | Need to know ΔSsys before deciding which relationship is true. |
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12 | ![](/olcweb/styles/shared/spacer.gif) | ![](/olcweb/styles/shared/spacer.gif) The compound 1-pentanol has an enthalpy of vaporization of 55.5 kJ/mol and an entropy of vaporization of 148 J/K.mol. Calculate its approximate boiling point. |
| ![](/olcweb/styles/shared/spacer.gif) | A)![](/olcweb/styles/shared/spacer.gif) | 102°C |
| ![](/olcweb/styles/shared/spacer.gif) | B)![](/olcweb/styles/shared/spacer.gif) | 375°C |
| ![](/olcweb/styles/shared/spacer.gif) | C)![](/olcweb/styles/shared/spacer.gif) | 45°C |
| ![](/olcweb/styles/shared/spacer.gif) | D)![](/olcweb/styles/shared/spacer.gif) | 25°C |
| ![](/olcweb/styles/shared/spacer.gif) | E)![](/olcweb/styles/shared/spacer.gif) | 93°C |
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13 | ![](/olcweb/styles/shared/spacer.gif) | ![](/olcweb/styles/shared/spacer.gif) The following reaction occurs at 298 K:
SO2(g) + NO2(g) →
SO3(g) + NO(g)
Data: Standard free energies of formation, ΔGºf (kJ/mol): SO2(g), -300.4; SO3(g), -370.4; NO(g), 86.7; NO2(g), 51.8
For the above reaction, which of the following conclusions is valid? |
| ![](/olcweb/styles/shared/spacer.gif) | A)![](/olcweb/styles/shared/spacer.gif) | K > 1, ΔHº
> 0 |
| ![](/olcweb/styles/shared/spacer.gif) | B)![](/olcweb/styles/shared/spacer.gif) | K > 1, ΔHº
< 0 |
| ![](/olcweb/styles/shared/spacer.gif) | C)![](/olcweb/styles/shared/spacer.gif) | K < 1, ΔHº > 0 |
| ![](/olcweb/styles/shared/spacer.gif) | D)![](/olcweb/styles/shared/spacer.gif) | K < 1, ΔHº < 0 |
| ![](/olcweb/styles/shared/spacer.gif) | E)![](/olcweb/styles/shared/spacer.gif) | none of the above |
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14 | ![](/olcweb/styles/shared/spacer.gif) | ![](/olcweb/styles/shared/spacer.gif) Consider the reaction:
N2(g) + 3H2(g) → 2NH3(g)
The standard free energy change for this reaction, ΔGº,
is -32.9 kJ. Calculate the equilibrium constant, K, at 25º
C. |
| ![](/olcweb/styles/shared/spacer.gif) | A)![](/olcweb/styles/shared/spacer.gif) | 13.3 |
| ![](/olcweb/styles/shared/spacer.gif) | B)![](/olcweb/styles/shared/spacer.gif) | 5.8 x
105 |
| ![](/olcweb/styles/shared/spacer.gif) | C)![](/olcweb/styles/shared/spacer.gif) | 2.5 |
| ![](/olcweb/styles/shared/spacer.gif) | D)![](/olcweb/styles/shared/spacer.gif) | 4.0 x
10-6 |
| ![](/olcweb/styles/shared/spacer.gif) | E)![](/olcweb/styles/shared/spacer.gif) | 9.1 x
108
|
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15 | ![](/olcweb/styles/shared/spacer.gif) | ![](/olcweb/styles/shared/spacer.gif) Calculate the equilibrium constant K for the following reaction at 25°C:
Data:
|
| ![](/olcweb/styles/shared/spacer.gif) | A)![](/olcweb/styles/shared/spacer.gif) | 6.85 |
| ![](/olcweb/styles/shared/spacer.gif) | B)![](/olcweb/styles/shared/spacer.gif) | 946 |
| ![](/olcweb/styles/shared/spacer.gif) | C)![](/olcweb/styles/shared/spacer.gif) | 1.06 x
10-3 |
| ![](/olcweb/styles/shared/spacer.gif) | D)![](/olcweb/styles/shared/spacer.gif) | –6.85 |
| ![](/olcweb/styles/shared/spacer.gif) | E)![](/olcweb/styles/shared/spacer.gif) | none of the above |
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