- A reaction has ΔH°rxn = -112 kJ and ΔS°rxn = 354 J/K. At what temperature is the change in entropy for the reaction equal to the change in entropy for the surroundings?
Problema 4
- What is the molar entropy of a pure crystal at 0 K, and what is the significance of the answer?
Problema 5
Problema 27
Which of these processes is spontaneous? a. the combustion of natural gas b. the extraction of iron metal from iron ore c. a hot drink cooling to room temperature d. drawing heat energy from the ocean's surface to power a ship
Problema 28
Which of these processes are nonspontaneous? Are the nonspontaneous processes impossible? a. a bike going up a hill b. a meteor falling to Earth c. obtaining hydrogen gas from liquid water d. a ball rolling down a hill
Problema 29
Two systems, each composed of two particles represented by circles, have 20 J of total energy. Which system, A or B, has the greater entropy? Why?
Problema 30
Two systems, each composed of three particles represented by circles, have 30 J of total energy. How many energetically equivalent ways can you distribute the particles in each system? Which system has greater entropy?
Problema 31
Calculate the change in entropy that occurs in the system when 1.00 mole of isopropyl alcohol (C3H8O) melts at its melting point (-89.5 °C). See Table 11.9 for heats of fusion.
Problema 32
Calculate the change in entropy that occurs in the system when 1.00 mole of diethyl ether (C4H10O) condenses from a gas to a liquid at its normal boiling point (34.6 °C). See Table 11.7 for heats of vaporization.
Problema 33
What is the change in entropy that occurs in the system when 45.0 g of acetone (C3H6O) freezes at its melting point (-94.8 °C)? Use Table 11.9 for the heats of fusion.
Problema 34
Calculate the change in entropy that occurs in the system when 55.0 g of water vaporizes from a liquid to a gas at its boiling point (100.0 °C). See Table 11.7 for heats of vaporization.
Problema 35a,c,d
Without doing any calculations, determine the sign of ΔSsys for each chemical reaction. a. 2 KClO3(s) → 2 KCl(s) + 3 O2(g) c. Na(s) + 2 Cl2(g) → NaCl(s) d. N2(g) + 3 H2(g) → 2 NH3(g)
Problema 35b
Without doing any calculations, determine the sign of ΔSsys for each chemical reaction. b. CH2=CH2( g) + H2( g) → CH3CH3( g)
Problema 36
Without doing any calculations, determine the sign of ΔSsys for each chemical reaction. a. Mg(s) + Cl2(g) → MgCl2(s) b. 2 H2S(g) + 3 O2(g) → 2 H2O(g) + 2 SO2(g) c. 2 O3(g) → 3 O2(g) d. HCl(g) + NH3(g) → NH4Cl(s)
Problema 37a
Without doing any calculations, determine the signs of ΔSsys and ΔS surr for each chemical reaction. In addition, predict under what temperatures (all temperatures, low temperatures, or high temperatures), if any, the reaction is spontaneous. a. C3H8(g) + 5 O2(g) → 3 CO2(g) + 4 H2O(g) ΔH°rxn = -2044 kJ
- Without doing any calculations, determine the signs of ΔSsys and ΔS surr for each chemical reaction. In addition, predict under what temperatures (all temperatures, low temperatures, or high temperatures), if any, the reaction is spontaneous: b. N2(g) + O2(g) → 2 NO(g), ΔH°rxn = +182.6 kJ; d. 4 NH3(g) + 5 O2(g) → 4 NO(g) + 6 H2O(g), ΔH°rxn = -906 kJ.
Problema 37b
Problema 37c
Without doing any calculations, determine the signs of ΔSsys and ΔSsurr for each chemical reaction. In addition, predict under what temperatures (all temperatures, low temperatures, or high temperatures), if any, the reaction is spontaneous. c. 2 N2(g) + O2(g) → 2 N2O(g) ΔH°rxn = +163.2 kJ
- Without doing any calculations, determine the signs of ΔS_sys and ΔS_surr for each chemical reaction. In addition, predict under what temperatures (all temperatures, low temperatures, or high temperatures), if any, the reaction is spontaneous. a. 2 CO(g) + O2(g) → 2 CO2(g) ΔH_rxn° = -566.0 kJ b. 2 NO2(g) → 2 NO(g) + O2(g) ΔH_rxn° = +113.1 kJ c. 2 H2(g) + O2(g) → 2 H2O(g) ΔH_rxn° = -483.6 kJ d. CO2(g) → C(s) + O2(g) ΔH_rxn° = +393.5 kJ
Problema 38
Problema 39d
Calculate ΔSsurr at the indicated temperature for each reaction. d. ΔH°rxn = +114 kJ; 77 K
- Given the values of ΔH° rxn, ΔS° rxn, and T, determine ΔSuniv and predict whether each reaction is spontaneous. Assume that all reactants and products are in their standard states. b. ΔH° rxn = -115 kJ; ΔS° rxn = +263 J/K; T = 298 K; d. ΔH° rxn = -115 kJ; ΔS° rxn = -263 J/K; T = 615 K.
Problema 41
Problema 41a
Given the values of ΔH°rxn, ΔS°rxn, and T, determine ΔSuniv and predict whether or not each reaction is spontaneous. (Assume that all reactants and products are in their standard states.) a. ΔH°rxn = +115 kJ; ΔS°rxn = -263 J/K; T = 298 K
Problema 41c
Given the values of ΔH°rxn, ΔS°rxn, and T, determine ΔSuniv and predict whether or not each reaction is spontaneous. (Assume that all reactants and products are in their standard states.) c. ΔH°rxn = -115 kJ; ΔS°rxn = -263 J/K; T = 298 K
- Given the values of ΔH°rxn, ΔS°rxn, and T, determine ΔS°univ and predict whether or not each reaction is spontaneous. (Assume that all reactants and products are in their standard states.) a. ΔH°rxn = -95 kJ; ΔS°rxn = -157 J/K; T = 855 K b. ΔH°rxn = -95 kJ; ΔS°rxn = +157 J/K; T = 398 K
Problema 42
Problema 42a
Given the values of ΔH°rxn, ΔS°rxn, and T, determine ΔSuniv and predict whether or not each reaction is spontaneous. (Assume that all reactants and products are in their standard states.) a. ΔH°rxn = -95 kJ; ΔS°rxn = -157 J/K; T = 298 K
Problema 42c
Given the values of ΔH°rxn, ΔS°rxn, and T, determine ΔSuniv and predict whether or not each reaction is spontaneous. (Assume that all reactants and products are in their standard states.) c. ΔH°rxn = +95 kJ; ΔS°rxn = -157 J/K; T = 298 K
Problema 43
Calculate the change in Gibbs free energy for each set of ΔHrxn, ΔSrxn, and T given in Problem 41. Predict whether or not each reaction is spontaneous at the temperature indicated. (Assume that all reactants and products are in their standard states.)
Problema 44
Calculate the change in Gibbs free energy for each of the sets of ΔHrxn, ΔSrxn, and T given in Problem 42. Predict whether or not each reaction is spontaneous at the temperature indicated. (Assume that all reactants and products are in their standard states.)
Problema 45
Calculate the free energy change for this reaction at 25 °C. Is the reaction spontaneous? (Assume that all reactants and products are in their standard states.) C3H8(g) + 5 O2(g) → 3 CO2(g) + 4 H2O(g) ΔH°rxn = -2217 kJ; ΔS°rxn = 101.1 J/K
Problema 46
Calculate the free energy change for this reaction at 25 °C. Is the reaction spontaneous? (Assume that all reactants and products are in their standard states.) 2 Ca(s) + O2( g) → 2 CaO(s) ΔH°rxn = -1269.8 kJ; ΔS°rxn = -364.6 J/K
Problema 47
Fill in the blanks in the table. Both ΔH and ΔS refer to the system.
Problema 48
Predict the conditions (high temperature, low temperature, all temperatures, or no temperatures) under which each reaction is spontaneous. a. H2O(g) → H2O(l) b. CO2(s) → CO2(g) c. H2(g) → 2 H(g) d. 2 NO2(g) → 2 NO(g) + O2(g) (endothermic)
Ch.18 - Free Energy and Thermodynamics
