Ch.18 - Free Energy and Thermodynamics

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Tro 4th Edition

Ch.18 - Free Energy and Thermodynamics

문제 4

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?

문제 5

What is the molar entropy of a pure crystal at 0 K, and what is the significance of the answer?

문제 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

문제 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

문제 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?

문제 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?

문제 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.

문제 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.

문제 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.

문제 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.

문제 35a,c,d

Without doing any calculations, determine the sign of ΔS_sys 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)

문제 35b

Without doing any calculations, determine the sign of ΔS_sys for each chemical reaction. b. CH₂=CH₂( g) + H₂( g) → CH₃CH₃( g)

문제 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)

문제 37a

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. C₃H₈(g) + 5 O₂(g) → 3 CO₂(g) + 4 H₂O(g) ΔH°_rxn = -2044 kJ

문제 37b

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.

문제 37c

문제 38

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

문제 39d

Calculate ΔS_surrat the indicated temperature for each reaction. d. ΔH°_rxn= +114 kJ; 77 K

문제 41

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.

문제 41a

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 = +115 kJ; ΔS°_rxn = -263 J/K; T = 298 K

문제 41c

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.) c. ΔH°_rxn = -115 kJ; ΔS°_rxn = -263 J/K; T = 298 K

문제 42

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

문제 42a

문제 42c

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.) c. ΔH°_rxn = +95 kJ; ΔS°_rxn = -157 J/K; T = 298 K

문제 43

Calculate the change in Gibbs free energy for each set of ΔH_rxn, ΔS_rxn, 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.)

문제 44

Calculate the change in Gibbs free energy for each of the sets of ΔH_rxn, ΔS_rxn, 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.)

문제 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

문제 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

문제 47

Fill in the blanks in the table. Both ΔH and ΔS refer to the system.

문제 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)