CHEM 202 HOMEWORK 2
Chapter Two
1. Arrange the following substances in order of increasing entropy at 25
°C : (a) CH3OH(l), (b) CO(g), (c) MgCO3(s), (d) H2O(l), (e) Ni(s).
Given the reasons for your arrangement?
2. Using the data in the provided appendix, Calculate the standard entropy changes for the following reactions at 25 °C:
(𝑎) S𝑂3(𝑔) + 𝐻2𝑂(𝑙) → 𝐻2𝑆𝑂4(𝑙)
(𝑏) SO2(𝑠) + 𝑁𝑂2(𝑔) → 𝑆𝑂3(𝑔) + 𝑁𝑂(𝑔)
3. Without consulting the provided appendix, predict whether the entropy change is positive or negative for each of the following reactions. Given reasons for your predictions.
(𝑎) CH4(𝑔) + 𝐻2𝑂(𝑔) → 𝐶𝑂(𝑔) + 3𝐻2(𝑔) (𝑏) C(𝑠) + 𝑂2 → 𝐶𝑂2(𝑔)
(𝑐) 𝐻2𝑂2(𝑙) → 𝐻2(𝐿) + 1 2⁄ 𝑂2(𝑔) (𝑑) N2(𝑔) → 2𝑁(𝑔)
4. Calculate ΔG° for the following reactions at 25 °C using the provided appendix:
(𝑎) SO2(𝑔) + 𝑁𝑂2(𝑔) → 𝑆𝑂3(𝑔) + 𝑁𝑂(𝑔) (𝑏) CuS(𝑠) + 𝐻2(𝑔) → 𝐻2𝑆(𝑔) + 𝐶𝑢(𝑠) (𝑐) Si𝑂2(𝑠) + 𝑃𝑏(𝑠) → 𝑃𝑏𝑂2(𝑠) + 𝑆𝑖(𝑠)
5. From the values of ΔH and ΔS, predict which of the following reactions would be spontaneous at 25°C : reaction A: ΔH=
10.5kJ/mol, ΔS=30J/K. mol, reaction B ΔH= 1.8kJ/mol, ΔS= -113J/K.
mol. If either of the reaction is nonspontaneous at 25 °C, at what temperature might it become spontaneous?
6. Calculate KP for the the decomposition of water reaction at 25 °C:
𝐻2𝑂(𝑙) ↔ 2𝐻2(𝑔) + 𝑂2(g) Δ𝐺𝑓°(𝐻2𝑂(𝑙)) = -237.2 kJ/mol
CHEM 202 HOMEWORK 2
7. HI has a normal boiling point of -35.4C, and its molar heat of vaporization is 21.16 kJ/mol. Calculate the molar entropy of vaporization ?
8. Calculate Kp at 298 K for the reaction SO2(g) + NO2(g) → SO3(g) + NO(g).
9. For the reaction 2C(graphite) + H2(g) → C2H2(g), G= +209.2 kJ/mol at 25C. If P(H2) = 100. atm, and P(C2H2) = 0.10 atm, calculate G for this reaction. Calculate G for this reaction ?
