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Problem 67
Determine ΔG° for the reaction: Fe2O3(s) + 3 CO(g) → 2 Fe(s) + 3 CO2(g) Use the following reactions with known ΔG°rxn values:
2 Fe(s) + 3/2 O2(g) → Fe2O3(s) ΔG°rxn = -742.2 kJ
CO(g) + 12 O2( g) → CO2(g) ΔG°rxn = -257.2 kJ
- Calculate ΔG°rxn for the reaction: CaCO3(s) → CaO(s) + CO2(g). Use the following reactions and given ΔG°rxn values: Ca(s) + CO2(g) + 1/2 O2(g) → CaCO3(s) ΔG°rxn = -734.4 kJ, 2 Ca(s) + O2(g) → 2 CaO(s) ΔG°rxn = -1206.6 kJ.
Problem 68
- Consider the sublimation of iodine at 25.0 °C: I2(s) → I2(g). a. Find ΔG°rxn at 25.0 °C.
Problem 69
Problem 69b
Consider the sublimation of iodine at 25.0 °C : I2(s) → I2(g) b. Find ΔG°rxn at 25.0 °C under the following nonstandard conditions: i. PI2 = 1.00 mmHg ii. PI2 = 0.100 mmHg
Problem 69c
Consider the sublimation of iodine at 25.0 °C : I2(s) → I2(g) c. Explain why iodine spontaneously sublimes in open air at 25.0 °C
Problem 70a
Consider the evaporation of methanol at 25.0 °C : CH3OH(l) → CH3OH(g) a. Find ΔG°r at 25.0 °C.
Problem 70b
Consider the evaporation of methanol at 25.0 °C : CH3OH(l) → CH3OH(g) b. Find ΔGr at 25.0 °C under the following nonstandard conditions: i. PCH3OH = 150.0 mmHg ii. PCH3OH = 100.0 mmHg iii. PCH3OH = 10.0 mmHg
Problem 70c
Consider the evaporation of methanol at 25.0 °C : CH3OH(l) → CH3OH(g) c. Explain why methanol spontaneously evaporates in open air at 25.0 °C
- Consider the reaction: CH3OH(g) → CO(g) + 2 H2(g). Calculate ΔG for this reaction at 25 °C under the following conditions: i. PCH3OH = 0.855 atm ii. PCO = 0.125 atm iii. PH2 = 0.183 atm.
Problem 71
Problem 72
Consider the reaction: CO2(g) + CCl4(g) ⇌ 2 COCl2(g) Calculate ΔG for this reaction at 25 °C under the following conditions: i. PCO2 = 0.112 atm ii. PCCl4 = 0.174 atm iii. PCOCl2 = 0.744 atm
Problem 73a
Use data from Appendix IIB to calculate the equilibrium constants at 25 °C for each reaction. a. 2 CO(g) + O2(g) ⇌ 2 CO2(g)
Problem 73b
Use data from Appendix IIB to calculate the equilibrium constants at 25 °C for each reaction. b. 2 H2S(g) ⇌ 2 H2(g) + S2(g)
- Use data from Appendix IIB to calculate the equilibrium constants at 25 °C for each reaction. ΔG°f for BrCl(g) is -1.0 kJ/mol. a. 2 NO2(g) ⇌ N2O4(g) b. Br2(g) + Cl2(g) ⇌ 2 BrCl(g)
Problem 74
- Consider the reaction: CO(g) + 2 H2(g) ⇌ CH3OH(g) with Kp = 2.26 * 10^4 at 25°C. Calculate ΔG°rxn for the reaction at 25°C under each of the following conditions: a. standard conditions b. at equilibrium c. PCH3OH = 1.0 atm; PCO = PH2 = 0.010 atm
Problem 75
Problem 76a
Consider the reaction: I2(g) + Cl2(g) ⇌ 2 ICl(g) Kp = 81.9 at 25 °C Calculate ΔGrxn for the reaction at 25 °C under each of the following conditions: a. standard conditions
Problem 76b
Consider the reaction: I2(g) + Cl2(g) ⇌ 2 ICl(g) Kp = 81.9 at 25 °C Calculate ΔGrxn for the reaction at 25 °C under each of the following conditions: b. at equilibrium
Problem 76c
Consider the reaction: I2(g) + Cl2(g) ⇌ 2 ICl(g) Kp = 81.9 at 25 °C Calculate ΔGrxn for the reaction at 25 °C under each of the following conditions: c. PICl = 2.55 atm; PI2 = 0.325 atm; PCl2 = 0.221 atm
- Is the value of the equilibrium constant at 525 K for each reaction in Problem 73 estimated correctly?
Problem 77
- Estimate the value of the equilibrium constant at 655 K for each reaction in Problem 74. (ΔHf° for BrCl is 14.6 kJ/mol.)
Problem 78
Problem 80
Consider the reaction: 2 NO(g) + O2(g) ⇌ 2 NO2(g) The following data show the equilibrium constant for this reaction measured at several different temperatures. Use the data to find ΔH°rxn and ΔS°rxn for the reaction.
Problem 81
The change in enthalpy (ΔH°rxn) for a reaction is -25.8 kJ/mol. The equilibrium constant for the reaction is 1.4⨉103 at 298 K. What is the equilibrium constant for the reaction at 655 K?
Problem 82
A reaction has an equilibrium constant of 8.5⨉103 at 298 K. At 755 K, the equilibrium constant is 0.65. Find ΔH°rxn for the reaction.
Problem 83a
Determine the sign of ΔSsys for each process. a. water boiling
Problem 83b
Determine the sign of ΔSsys for each process. b. water freezing
- Our atmosphere is composed primarily of nitrogen and oxygen, which coexist at 25 °C without reacting to any significant extent. However, the two gases can react to form nitrogen monoxide according to the reaction: N2(g) + O2(g) → 2 NO(g). a. Calculate ΔG° and Kp for this reaction at 298 K. Is the reaction spontaneous? b. Estimate ΔG° at 2000 K. Does the reaction become more spontaneous as temperature increases?
Problem 85
Problem 86
Nitrogen dioxide, a pollutant in the atmosphere, can combine with water to form nitric acid. One of the possible reactions is shown here. Calculate ΔG° and Kp for this reaction at 25 °C and comment on the spontaneity of the reaction. 3 NO2(g) + H2O(l)→ 2 HNO3(aq) + NO(g)
Problem 87
Ethene (C2H4) can be halogenated by the reaction: C2H4(g) + X2(g) → C2H4X2(g) where X2 can be Cl2, Br2, or I2. Use the thermodynamic data given to calculate ΔH°, ΔS°, ΔG°, and Kp for the halogenation reaction by each of the three halogens at 25 °C. Which reaction is most spontaneous? Least spontaneous? What is the main factor responsible for the difference in the spontaneity of the three reactions? Does higher temperature make the reactions more spontaneous or less spontaneous?
Compound ΔH°f (kJ/mol) S° (J/mol·K)
C2H4Cl2(g) -129.7 308.0
C2H4Br2(g) +38.3 330.6
C2H4I2(g) +66.5 347.8
Problem 88
H2 reacts with the halogens (X2) according to the reaction: H2(g) + X2(g) → 2 HX(g) where X2 can be Cl2, Br2, or I2. Use the thermodynamic data in Appendix IIB to calculate ΔH°, ΔS°, ΔG°, and Kp for the reaction between hydrogen and each of the three halogens. Which reaction is most spontaneous? Least spontaneous? What is the main factor responsible for the difference in the spontaneity of the three reactions? Does higher temperature make the reactions more spontaneous or less spontaneous?
Problem 89a
Consider this reaction occurring at 298 K: N2O(g) + NO2(g) ⇌ 3 NO(g) a. Show that the reaction is not spontaneous under standard conditions by calculating ΔG°rxn.
Problem 89b
Consider this reaction occurring at 298 K: N2O(g) + NO2(g) ⇌ 3 NO(g) b. If a reaction mixture contains only N2O and NO2 at partial pressures of 1.0 atm each, the reaction will be spontaneous until some NO forms in the mixture. What maximum partial pressure of NO builds up before the reaction ceases to be spontaneous?