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Chemistry | 12th Edition | ISBN: 9780078021510 | Authors: Raymond Chang; Kenneth Goldsby

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Chapter 17 Problems

Chapter: 17 Problem: 17.1

Chemistry 12
Explain what is meant by a spontaneous process. Give two examples each of spontaneous and nonspontaneous processes.

Chapter: 17 Problem: 17.2

Chemistry 12
Which of the following processes are spontaneous and which are nonspontaneous? (a) dissolving table salt (NaCl) in hot soup; (b) climbing Mt. Everest; (c) spreading fragrance in a room by removing the cap from a perfume bottle; (d) separating helium and neon from a mixture of the gases

Chapter: 17 Problem: 17.3

Chemistry 12
Which of the following processes are spontaneous and which are nonspontaneous at a given temperature? (a) NaNO3(s) H2O NaNO3(aq) saturated soln (b) NaNO3(s) H2O NaNO3(aq) unsaturated soln (c) NaNO3(s) H2O NaNO3(aq) supersaturated soln

Chapter: 17 Problem: 17.4

Chemistry 12
Define entropy. What are the units of entropy?

Chapter: 17 Problem: 17.5

Chemistry 12
How does the entropy of a system change for each of the following processes? (a) A solid melts. (b) A liquid freezes. (c) A liquid boils. (d) A vapor is converted to a solid. (e) A vapor condenses to a liquid. (f) A solid sublimes. (g) Urea dissolves in water.

Chapter: 17 Problem: 17.6

Chemistry 12
Consider the arrangement in Figure 17.1. Because the volume of the two bulbs is the same, the probability of finding a molecule in either bulb is 1 2. Calculate the probability of all the molecules ending up in the same bulb if the number is (a) 2, (b) 100, and (c) 6 3 1023. Based on your results, ex

Chapter: 17 Problem: 17.7

Chemistry 12
State the second law of thermodynamics in words and express it mathematically

Chapter: 17 Problem: 17.8

Chemistry 12
State the third law of thermodynamics and explain its usefulness in calculating entropy values.

Chapter: 17 Problem: 17.9

Chemistry 12
For each pair of substances listed here, choose the one having the larger standard entropy value at 25C. The same molar amount is used in the comparison. Explain the basis for your choice. (a) Li(s) or Li(l); (b) C2H5OH(l) or CH3OCH3(l) (Hint: Which molecule can hydrogen-bond?); (c) Ar(g) or Xe(g);

Chapter: 17 Problem: 17.1b

Chemistry 12
Arrange the following substances (1 mole each) in order of increasing entropy at 25C: (a) Ne(g), (b) SO2(g), (c) Na(s), (d) NaCl(s), (e) H2(g). Give the reasons for your arrangement

Chapter: 17 Problem: 17.11

Chemistry 12
Using the data in Appendix 3, calculate the standard entropy changes for the following reactions at 25C: (a) S(s) 1 O2(g) SO2(g) (b) MgCO3(s) MgO(s) 1 CO2(g)

Chapter: 17 Problem: 17.12

Chemistry 12
Using the data in Appendix 3, calculate the standard entropy changes for the following reactions at 25C: (a) H2(g) 1 CuO(s) Cu(s) 1 H2O(g) (b) 2Al(s) 1 3ZnO(s) Al2O3(s) 1 3Zn(s) (c) CH4(g) 1 2O2(g) CO2(g) 1 2H2O(l)

Chapter: 17 Problem: 17.13

Chemistry 12
Without consulting Appendix 3, predict whether the entropy change is positive or negative for each of the following reactions. Give reasons for your predictions. (a) 2KClO4(s) 2KClO3(s) 1 O2(g) (b) H2O(g) H2O(l) (c) 2Na(s) 1 2H2O(l) 2NaOH(aq) 1 H2(g) (d) N2(g) 2N(g)

Chapter: 17 Problem: 17.14

Chemistry 12
State whether the sign of the entropy change expected for each of the following processes will be positive or negative, and explain your predictions. (a) PCl3(l) 1 Cl2(g) PCl5(s) (b) 2HgO(s) 2Hg(l) 1 O2(g) (c) H2(g) 2H(g) (d) U(s) 1 3F2(g) UF6(s)

Chapter: 17 Problem: 17.15

Chemistry 12
Define free energy. What are its units?

Chapter: 17 Problem: 17.16

Chemistry 12
Very concentrated NaOH solutions should not be stored in Pyrex glassware. Why? (Hint: See Section 11.7.

Chapter: 17 Problem: 17.17

Chemistry 12
Calculate DG for the following reactions at 25C: (a) N2(g) 1 O2(g) 2NO(g) (b) H2O(l) H2O(g) (c) 2C2H2(g) 1 5O2(g) 4CO2(g) 1 2H2O(l) (Hint: Look up the standard free energies of formation of the reactants and products in Appendix 3.)

Chapter: 17 Problem: 17.18

Chemistry 12
Calculate DG for the following reactions at 25C: (a) 2Mg(s) 1 O2(g) 2MgO(s) (b) 2SO2(g) 1 O2(g) 2SO3(g) (c) 2C2H6(g) 1 7O2(g) 4CO2(g) 1 6H2O(l) See Appendix 3 for thermodynamic data.

Chapter: 17 Problem: 17.19

Chemistry 12
From the values of DH and DS, predict which of the following reactions would be spontaneous at 25C: Reaction A: DH 5 10.5 kJ/mol, DS 5 30 J/K ? mol; reaction B: DH 5 1.8 kJ/mol, DS 5 2113 J/K ? mol. If either of the reactions is nonspontaneous at 25C, at what temperature might it become spontaneous?

Chapter: 17 Problem: 17.2b

Chemistry 12
Find the temperatures at which reactions with the following DH and DS values would become spontaneous: (a) DH 5 2126 kJ/mol, DS 5 84 J/K ? mol; (b) DH 5 211.7 kJ/mol, DS 5 2105 J/K ? mol.

Chapter: 17 Problem: 17.21

Chemistry 12
Explain the difference between DG and DG.

Chapter: 17 Problem: 17.22

Chemistry 12
Explain why Equation (17.14) is of great importance in chemistry.

Chapter: 17 Problem: 17.23

Chemistry 12
Calculate KP for the following reaction at 25C: H2(g) 1 I2(g) 2HI(g) G 5 2.60 kJ/mol

Chapter: 17 Problem: 17.24

Chemistry 12
For the autoionization of water at 25C, H2O(l) H1(aq) 1 OH2(aq) Kw is 1.0 3 10214. What is DG for the process?

Chapter: 17 Problem: 17.25

Chemistry 12
Consider the following reaction at 25C: Fe(OH)2 (s) Fe21(aq) 1 2OH2(aq) Calculate DG for the reaction. Ksp for Fe(OH)2 is 1.6 3 10214

Chapter: 17 Problem: 17.26

Chemistry 12
Calculate DG and KP for the following equilibrium reaction at 25C. 2H2O(g) 2H2(g) 1 O2(g)

Chapter: 17 Problem: 17.27

Chemistry 12
(a) Calculate DG and KP for the following equilibrium reaction at 25C. The DGf values are 0 for Cl2(g), 2286 kJ/mol for PCl3(g), and 2325 kJ/mol for PCl5(g). PCl5(g) PCl3(g) 1 Cl2(g) (b) Calculate DG for the reaction if the partial pressures of the initial mixture are PPCl5 5 0.0029 atm, PPCl3 5 0.2

Chapter: 17 Problem: 17.28

Chemistry 12
The equilibrium constant (KP) for the reaction H2(g) 1 CO2(g) H2O(g) 1 CO(g) is 4.40 at 2000 K. (a) Calculate DG for the reaction. (b) Calculate DG for the reaction when the partial pressures are PH2 5 0.25 atm, PCO2 5 0.78 atm, PH2O 5 0.66 atm, and PCO 5 1.20 atm

Chapter: 17 Problem: 17.29

Chemistry 12
Consider the decomposition of calcium carbonate: CaCO3(s) CaO(s) 1 CO2(g) Calculate the pressure in atm of CO2 in an equilibrium process (a) at 25C and (b) at 800C. Assume that DH 5 177.8 kJ/mol and DS 5 160.5 J/K ? mol for the temperature range.

Chapter: 17 Problem: 17.3b

Chemistry 12
The equilibrium constant KP for the reaction CO(g) 1 Cl2(g) COCl2(g) is 5.62 3 1035 at 25C. Calculate DGf for COCl2 at 25C.

Chapter: 17 Problem: 17.31

Chemistry 12
At 25C, DG for the process H2O(l) H2O(g) is 8.6 kJ/mol. Calculate the vapor pressure of water at this temperature.

Chapter: 17 Problem: 17.32

Chemistry 12
Calculate DG for the process C(diamond) C(graphite) Is the formation of graphite from diamond favored at 25C? If so, why is it that diamonds do not become graphite on standing?

Chapter: 17 Problem: 17.33

Chemistry 12
What is a coupled reaction? What is its importance in biological reactions?

Chapter: 17 Problem: 17.34

Chemistry 12
What is the role of ATP in biological reactions?

Chapter: 17 Problem: 17.35

Chemistry 12
Referring to the metabolic process involving glucose on p. 801, calculate the maximum number of moles of ATP that can be synthesized from ADP from the breakdown of one mole of glucose

Chapter: 17 Problem: 17.36

Chemistry 12
In the metabolism of glucose, the first step is the conversion of glucose to glucose 6-phosphate: glucose 1 H3PO4 glucose 6-phosphate 1 H2O G 5 13.4 kJ/mol Because DG is positive, this reaction does not favor the formation of products. Show how this reaction can be made to proceed by coupling it wit

Chapter: 17 Problem: 17.37

Chemistry 12
Explain the following nursery rhyme in terms of the second law of thermodynamics. Humpty Dumpty sat on a wall; Humpty Dumpty had a great fall. All the Kings horses and all the Kings men Couldnt put Humpty together again.

Chapter: 17 Problem: 17.38

Chemistry 12
Calculate DG for the reaction H2O(l) H1(aq) 1 OH2(aq) at 25C for the following conditions: (a) [H 1] 5 1.0 3 1027 M, [OH2] 5 1.0 3 1027 M (b) [H 1] 5 1.0 3 1023 M, [OH2] 5 1.0 3 1024 M (c) [H 1] 5 1.0 3 10212 M, [OH2] 5 2.0 3 1028 M (d) [H 1] 5 3.5 M, [OH2] 5 4.8 3 1024 M

Chapter: 17 Problem: 17.39

Chemistry 12
Calculate the DSsoln for the following processes: (a) NH4NO3(s) NH4 1(aq) 1 NO3 2(aq) and (b) FeCl3(s) Fe31(aq) 1 3Cl2(aq). Give a qualitative explanation for the signs

Chapter: 17 Problem: 17.4b

Chemistry 12
The following reaction is spontaneous at a certain temperature T. Predict the sign of DSsurr. 8n

Chapter: 17 Problem: 17.41

Chemistry 12
Which of the following thermodynamic functions are associated only with the first law of thermodynamics: S, U, G, and H?

Chapter: 17 Problem: 17.42

Chemistry 12
A student placed 1 g of each of three compounds A, B, and C in a container and found that after 1 week no change had occurred. Offer some possible explanations for the fact that no reactions took place. Assume that A, B, and C are totally miscible liquids.

Chapter: 17 Problem: 17.43

Chemistry 12
Use the data in Appendix 3 to calculate the equilibrium constant for the reaction AgI(s) Ag1(aq) 1 I 2(aq) at 25C. Compare your result with the Ksp value in Table 16.2.

Chapter: 17 Problem: 17.44

Chemistry 12
Predict the signs of DH, DS, and DG of the system for the following processes at 1 atm: (a) ammonia melts at 260C, (b) ammonia melts at 277.7C, (c) ammonia melts at 2100C. (The normal melting point of ammonia is 277.7C.)

Chapter: 17 Problem: 17.45

Chemistry 12
Consider the following facts: Water freezes spontaneously at 25C and 1 atm, and ice has a more ordered structure than liquid water. Explain how a spontaneous process can lead to a decrease in entropy.

Chapter: 17 Problem: 17.46

Chemistry 12
Ammonium nitrate (NH4NO3) dissolves spontaneously and endothermically in water. What can you deduce about the sign of DS for the solution process?

Chapter: 17 Problem: 17.47

Chemistry 12
Calculate the equilibrium pressure of CO2 due to the decomposition of barium carbonate (BaCO3) at 25C.

Chapter: 17 Problem: 17.48

Chemistry 12
(a) Troutons rule states that the ratio of the molar heat of vaporization of a liquid (DHvap) to its boiling point in kelvins is approximately 90 J/K ? mol. Use the following data to show that this is the case and explain why Troutons rule holds true: tbp(8C) DHvap(kJ/mol) Benzene 80.1 31.0 Hexane 68

Chapter: 17 Problem: 17.49

Chemistry 12
Referring to Problem 17.48, explain why the ratio is considerably smaller than 90 J/K ? mol for liquid HF

Chapter: 17 Problem: 17.5b

Chemistry 12
Carbon monoxide (CO) and nitric oxide (NO) are polluting gases contained in automobile exhaust. Under suitable conditions, these gases can be made to react to form nitrogen (N2) and the less harmful carbon dioxide (CO2). (a) Write an equation for this reaction. (b) Identify the oxidizing and reducing

Chapter: 17 Problem: 17.51

Chemistry 12
For reactions carried out under standard-state conditions, Equation (17.10) takes the form DG 5 DH 2 TDS. (a) Assuming DH and DS are independent of temperature, derive the equation ln K2 K1 5 H R a T2 2 T1 T1T2 b where K1 and K2 are the equilibrium constants at T1 and T2, respectively. (b) Given that

Chapter: 17 Problem: 17.52

Chemistry 12
Use the thermodynamic data in Appendix 3 to calculate the Ksp of AgCl.

Chapter: 17 Problem: 17.53

Chemistry 12
Consider the reaction A B 1 C at 298 K. Given that the forward rate constant (kf) is 0.46 s21 and the reverse rate constant (kr) is 1.5 3 1022 /M ? s, calculate DG of the reaction.

Chapter: 17 Problem: 17.54

Chemistry 12
The Ksp of AgCl is given in Table 16.2. What is its value at 60C? [Hint: You need the result of Problem 17.51(a) and the data in Appendix 3 to calculate DH.]

Chapter: 17 Problem: 17.55

Chemistry 12
Under what conditions does a substance have a standard entropy of zero? Can a substance ever have a negative standard entropy?

Chapter: 17 Problem: 17.56

Chemistry 12
Water gas, a mixture of H2 and CO, is a fuel made by reacting steam with red-hot coke (a by-product of coal distillation): H2O(g) 1 C(s) CO(g) 1 H2(g) From the data in Appendix 3, estimate the temperature at which the reaction begins to favor the formation of products.

Chapter: 17 Problem: 17.57

Chemistry 12
Consider the following Brnstead acid-base reaction at 25C: HF(aq) 1 Cl2(aq) HCl(aq) 1 F2(aq) (a) Predict whether K will be greater or smaller than unity. (b) Does DS or DH make a greater contribution to DG? (c) Is DH likely to be positive or negative?

Chapter: 17 Problem: 17.58

Chemistry 12
Crystallization of sodium acetate from a supersaturated solution occurs spontaneously (see p. 519). What can you deduce about the signs of DS and DH?

Chapter: 17 Problem: 17.59

Chemistry 12
Consider the thermal decomposition of CaCO3: CaCO3(s) CaO(s) 1 CO2(g) The equilibrium vapor pressures of CO2 are 22.6 mmHg at 700C and 1829 mmHg at 950C. Calculate the standard enthalpy of the reaction. [Hint: See Problem 17.51(a).]

Chapter: 17 Problem: 17.6b

Chemistry 12
A certain reaction is spontaneous at 72C. If the enthalpy change for the reaction is 19 kJ/mol, what is the minimum value of DS (in J/K ? mol) for the reaction?

Chapter: 17 Problem: 17.61

Chemistry 12
Predict whether the entropy change is positive or negative for each of these reactions: (a) Zn(s) 1 2HCl(aq) ZnCl2(aq) 1 H2(g) (b) O(g) 1 O(g) O2(g) (c) NH4NO3(s) N2O(g) 1 2H2O(g) (d) 2H2O2(l) 2H2O(l) 1 O2(g)

Chapter: 17 Problem: 17.62

Chemistry 12
The reaction NH3(g) 1 HCl(g) NH4Cl(s) proceeds spontaneously at 25C even though there is a decrease in the number of microstates of the system (gases are converted to a solid). Explain.

Chapter: 17 Problem: 17.63

Chemistry 12
Use the following data to determine the normal boiling point, in kelvins, of mercury. What assumptions must you make in order to do the calculation? Hg(l): Hf 5 0 (by definition) S 5 77.4 J/K ? mol Hg(g): Hf 5 60.78 kJ/mol S 5 174.7 J/K ? mol

Chapter: 17 Problem: 17.64

Chemistry 12
The molar heat of vaporization of ethanol is 39.3 kJ/mol and the boiling point of ethanol is 78.3C. Calculate DS for the vaporization of 0.50 mol ethanol.

Chapter: 17 Problem: 17.65

Chemistry 12
A certain reaction is known to have a DG value of 2122 kJ/mol. Will the reaction necessarily occur if the reactants are mixed together?

Chapter: 17 Problem: 17.66

Chemistry 12
In the Mond process for the purification of nickel, carbon monoxide is reacted with heated nickel to produce Ni(CO)4, which is a gas and can therefore be separated from solid impurities: Ni(s) 1 4CO(g) Ni(CO)4(g) Given that the standard free energies of formation of CO(g) and Ni(CO)4(g) are 2137.3 k

Chapter: 17 Problem: 17.67

Chemistry 12
Calculate DG and KP for the following processes at 25C: (a) H2(g) 1 Br2(l) 2HBr(g) (b) 1 2H2(g) 1 1 2Br2(l) HBr(g) Account for the differences in DG and KP obtained for (a) and (b)

Chapter: 17 Problem: 17.68

Chemistry 12
Calculate the pressure of O2 (in atm) over a sample of NiO at 25C if DG 5 212 kJ/mol for the reaction NiO(s) Ni(s) 1 1 2O2(g)

Chapter: 17 Problem: 17.69

Chemistry 12
Comment on the statement: Just talking about entropy increases its value in the universe.

Chapter: 17 Problem: 17.7b

Chemistry 12
For a reaction with a negative DG value, which of the following statements is false? (a) The equilibrium constant K is greater than one, (b) the reaction is spontaneous when all the reactants and products are in their standard states, and (c) the reaction is always exothermic

Chapter: 17 Problem: 17.71

Chemistry 12
Consider the reaction N2(g) 1 O2(g) 2NO(g) Given that DG for the reaction at 25C is 173.4 kJ/ mol, (a) calculate the standard free energy of formation of NO, and (b) calculate KP of the reaction. (c) One of the starting substances in smog formation is NO. Assuming that the temperature in a running a

Chapter: 17 Problem: 17.72

Chemistry 12
Heating copper(II) oxide at 400C does not produce any appreciable amount of Cu: CuO(s) Cu(s) 1 1 2O2(g) G 5 127.2 kJ/mol However, if this reaction is coupled to the conversion of graphite to carbon monoxide, it becomes spontaneous. Write an equation for the coupled process and calculate the equilibr

Chapter: 17 Problem: 17.73

Chemistry 12
The internal engine of a 1200-kg car is designed to run on octane (C8H18), whose enthalpy of combustion is 5510 kJ/mol. If the car is moving up a slope, calculate the maximum height (in meters) to which the car can be driven on 1.0 gallon of the fuel. Assume that the engine cylinder temperature is 22

Chapter: 17 Problem: 17.74

Chemistry 12
Consider the decomposition of magnesium carbonate: MgCO3(s) MgO(s) 1 CO2(g) Calculate the temperature at which the decomposition begins to favor products. Assume that both DH and DS are independent of temperature.

Chapter: 17 Problem: 17.75

Chemistry 12
(a) Over the years there have been numerous claims about perpetual motion machines, machines that will produce useful work with no input of energy. Explain why the first law of thermodynamics prohibits the possibility of such a machine existing. (b) Another kind of machine, sometimes called a perpetu

Chapter: 17 Problem: 17.76

Chemistry 12
The activity series in Section 4.4 shows that reaction (a) is spontaneous while reaction (b) is nonspontaneous at 25C: (a) Fe(s) 1 2H1 Fe21(aq) 1 H2(g) (b) Cu(s) 1 2H1 Cu21(aq) 1 H2(g) Use the data in Appendix 3 to calculate the equilibrium constant for these reactions and hence confirm that the ac

Chapter: 17 Problem: 17.77

Chemistry 12
The rate constant for the elementary reaction 2NO(g) 1 O2(g) 2NO2(g) is 7.1 3 109 /M2 ? s at 25C. What is the rate constant for the reverse reaction at the same temperature?

Chapter: 17 Problem: 17.78

Chemistry 12
The following reaction is the cause of sulfur deposits formed at volcanic sites (see p. 911): 2H2S(g) 1 SO2(g) 3S(s) 1 2H2O(g) It may also be used to remove SO2 from powerplant stack gases. (a) Identify the type of redox reaction it is. (b) Calculate the equilibrium constant (KP) at 25C and comment

Chapter: 17 Problem: 17.79

Chemistry 12
Describe two ways that you could measure DG of a reaction

Chapter: 17 Problem: 17.8b

Chemistry 12
The following reaction represents the removal of ozone in the stratosphere: 2O3(g) 3O2(g) Calculate the equilibrium constant (KP) for the reaction. In view of the magnitude of the equilibrium constant, explain why this reaction is not considered a major cause of ozone depletion in the absence of man

Chapter: 17 Problem: 17.81

Chemistry 12
A 74.6-g ice cube floats in the Arctic Sea. The temperature and pressure of the system and surroundings are at 1 atm and 0C. Calculate DSsys, DSsurr, and DSuniv for the melting of the ice cube. What can you conclude about the nature of the process from the value of DSuniv? (The molar heat of fusion o

Chapter: 17 Problem: 17.82

Chemistry 12
Comment on the feasibility of extracting copper from its ore chalcocite (Cu2S) by heating: Cu2S(s2 2Cu(s) 1 S(s) Calculate the DG for the overall reaction if the above process is coupled to the conversion of sulfur to sulfur dioxide. Given that DGf (Cu2S) 5 286.1 kJ/mol

Chapter: 17 Problem: 17.83

Chemistry 12
Active transport is the process in which a substance is transferred from a region of lower concentration to one of higher concentration. This is a nonspontaneous process and must be coupled to a spontaneous process, such as the hydrolysis of ATP. The concentrations of K1 ions in the blood plasma and

Chapter: 17 Problem: 17.84

Chemistry 12
Large quantities of hydrogen are needed for the synthesis of ammonia. One preparation of hydrogen involves the reaction between carbon monoxide and steam at 300C in the presence of a copper-zinc catalyst: CO(g) 1 H2O(g) CO2(g) 1 H2(g) Calculate the equilibrium constant (KP) for the reaction and the

Chapter: 17 Problem: 17.85

Chemistry 12
Shown here are the thermodynamic data for ethanol: DHf 8(kJ/mol) S8(J/K ? mol) liquid 2276.98 161.0 vapor 2235.1 282.7 Calculate the vapor pressure of ethanol at 25C. Assume the thermodynamic values are independent of temperature.

Chapter: 17 Problem: 17.86

Chemistry 12
The reaction shown here is spontaneous at a certain temperature T. What is the sign of DSsurr?

Chapter: 17 Problem: 17.87

Chemistry 12
Consider two carboxylic acids (acids that contain the COOH group): CH3COOH (acetic acid, Ka 5 1.8 3 1025 ) and CH2ClCOOH (chloroacetic acid, Ka 5 1.4 3 1023 ). (a) Calculate DG for the ionization of these acids at 25C. (b) From the equation DG 5 DH 2 TDS, we see that the contributions to the DG term

Chapter: 17 Problem: 17.88

Chemistry 12
Many hydrocarbons exist as structural isomers, which are compounds that have the same molecular formula but different structures. For example, both butane and isobutane have the same molecular formula of C4H10 (see Problem 11.19). Calculate the mole percent of these molecules in an equilibrium mixtur

Chapter: 17 Problem: 17.89

Chemistry 12
Use the thermodynamic data in Appendix 3 to determine the normal boiling point of liquid bromine. Assume the values are independent of temperature

Chapter: 17 Problem: 17.9b

Chemistry 12
In each of the following reactions, there is one species for which the standard entropy value is not listed in Appendix 3. Determine the S for that species. (a) The DSrxn for the reaction Na(s) Na(l) is 48.64 J/K ? mol. (b) The DSrxn for the re action 2S(monoclinic) 1 Cl2(g) S2Cl2(g) is 43.4 J/K ?

Chapter: 17 Problem: 17.91

Chemistry 12
A rubber band is stretched vertically by attaching a weight to one end and holding the other end by hand. On heating the rubber band with a hotair blower, it is observed to shrink slightly in length. Give a thermodynamic analysis for this behavior. (Hint: See the Chemistry in Action essay on p. 801.)

Chapter: 17 Problem: 17.92

Chemistry 12
One of the steps in the extraction of iron from its ore (FeO) is the reduction of iron(II) oxide by carbon monoxide at 900C: FeO(s) 1 CO(g) Fe(s) 1 CO2(g) If CO is allowed to react with an excess of FeO, calculate the mole fractions of CO and CO2 at equilibrium. State any assumptions.

Chapter: 17 Problem: 17.93

Chemistry 12
Derive the following equation G 5 RT ln (Q/K) where Q is the reaction quotient and describe how you would use it to predict the spontaneity of a reaction.

Chapter: 17 Problem: 17.94

Chemistry 12
The sublimation of carbon dioxide at 278C is CO2(s) CO2(g) Hsub 5 62.4 kJ/mol Calculate DSsub when 84.8 g of CO2 sublimes at this temperature

Chapter: 17 Problem: 17.95

Chemistry 12
Entropy has sometimes been described as times arrow because it is the property that determines the forward direction of time. Explain.

Chapter: 17 Problem: 17.96

Chemistry 12
Referring to Figure 17.1, we see that the probability of finding all 100 molecules in the same bulb is 8 3 10231. Assuming that the age of the universe is 13 billion years, calculate the time in seconds during which this event can be observed

Chapter: 17 Problem: 17.97

Chemistry 12
A student looked up the Gf , Hf , and S values for CO2 in Appendix 3. Plugging these values into Equation (17.10), he found that Gf ? Hf 2 TS at 298 K. What is wrong with his approach?

Chapter: 17 Problem: 17.98

Chemistry 12
Consider the following reaction at 298 K: 2H2(g) 1 O2(g) 2H2O(l) H 5 2571.6 kJ/mol Calculate DSsys, DSsurr, and DSuniv for the reaction

Chapter: 17 Problem: 17.99

Chemistry 12
As an approximation, we can assume that proteins exist either in the native (or physiologically functioning) state and the denatured state native denatured 810 The standard molar enthalpy and entropy of the denaturation of a certain protein are 512 kJ/mol and 1.60 kJ/K ? mol, respectively. Comment

Chapter: 17 Problem: 17.1c

Chemistry 12
Which of the following are not state functions: S, H, q, w, T?

Chapter: 17 Problem: 17.101

Chemistry 12
Which of the following is not accompanied by an increase in the entropy of the system? (a) mixing of two gases at the same temperature and pressure, (b) mixing of ethanol and water, (c) discharging a battery, (d) expansion of a gas followed by compression to its original temperature, pressure, and vo

Chapter: 17 Problem: 17.102

Chemistry 12
Hydrogenation reactions (for example, the process of converting CC bonds to CC bonds in food industry) are facilitated by the use of a transition metal catalyst, such as Ni or Pt. The initial step is the adsorption, or binding, of hydrogen gas onto the metal surface. Predict the signs of DH, DS, and

Chapter: 17 Problem: 17.103

Chemistry 12
Give a detailed example of each of the following, with an explanation: (a) a thermodynamically spontaneous process; (b) a process that would violate the first law of thermodynamics; (c) a process that would violate the second law of thermodynamics; (d) an irreversible process; (e) an equilibrium proc

Chapter: 17 Problem: 17.104

Chemistry 12
At 0 K, the entropy of carbon monoxide crystal is not zero but has a value of 4.2 J/K ? mol, called the residual entropy. According to the third law of thermodynamics, this means that the crystal does not have a perfect arrangement of the CO molecules. (a) What would be the residual entropy if the ar

Chapter: 17 Problem: 17.105

Chemistry 12
Comment on the correctness of the analogy sometimes used to relate a students dormitory room becoming untidy to an increase in entropy

Chapter: 17 Problem: 17.106

Chemistry 12
The standard enthalpy of formation and the standard entropy of gaseous benzene are 82.93 kJ/mol and 269.2 J/K ? mol, respectively. Calculate DH, DS, and DG for the process at 25C. C6H6(l) C6H6(g) Comment on your answers

Chapter: 17 Problem: 17.107

Chemistry 12
In chemistry, the standard state for a solution is 1 M (see Table 17.2). This means that each solute concentration expressed in molarity is divided by 1 M. In biological systems, however, we define the standard state for the H1 ions to be 1 3 1027 M because the physiological pH is about 7. Consequen

Chapter: 17 Problem: 17.108

Chemistry 12
The following diagram shows the variation of the equilibrium constant with temperature for the reaction I2(g) 2I(g) Calculate DG, DH, and DS for the reaction at 872 K. (Hint: See Problem 17.51.) ln K T2 1173 K T1 872 K K1 1.80 104 K2 0.0480 1DT 17

Chapter: 17 Problem: 17.109

Chemistry 12
Consider the gas-phase reaction between A2 (green) and B2 (red) to form AB at 298 K: A2(g) 1 B2(g) 2AB(g) G 5 23.4 kJ/mol (1) Which of the following reaction mixtures is at equilibrium? (2) Which of the following reaction mixtures has a negative DG value? (3) Which of the following reaction mixture

Chapter: 17 Problem: 17.11c

Chemistry 12
The KP for the reaction N2 1 3H2 2NH3 is 2.4 3 1023 at 720C. What is the minimum partial pressure of N2 required for the reaction to be spontaneous in the forward direction if the partial pressures of H2 and NH3 are 1.52 atm and 2.1 3 1022 atm, respectively?

Chapter: 17 Problem: 17.111

Chemistry 12
The table shown here lists the ion-product constant (Kw) of water at several temperatures. Determine graphically the DH for the ionization of water. Kw 0.113 3 0.292 3 1.008 3 2.917 3 5.4743 10214 10214 10214 10214 10214 t(C) 0 10 25 40 50 (Hint: See Problem 14.118.)

Chapter: 17 Problem: 17.112

Chemistry 12
The reaction NH3(g) 1 HCl(g) NH4Cl(s) is spontaneous at room temperature (see Figure 5.20). Estimate the temperature at which the reaction is no longer spontaneous under standard conditions.

Chapter: 17 Problem: 17.113

Chemistry 12
The boiling point of diethyl ether is 34.6C. Estimate (a) its molar heat of vaporization and (b) its vapor pressure at 20C. (Hint: See Problems 17.48 and 17.51.)

Chapter: 17 Problem: 17.114

Chemistry 12
Nicotine is the compound in tobacco responsible for addiction to smoking. While most of the nicotine in tobacco exists in the neutral form, roughly 90 percent of the nicotine in the bloodstream is protonated, as represented in the following chemical equation. Estimate DG for the reaction. N N CH3 N N

Chapter: 17 Problem: 17.115

Chemistry 12
Estimate DS for the process depicted in Figure 17.1(a) if the apparatus contained 20 molecules in the flask on the left in the initial distribution, and each flask contained 10 molecules in the final distribution. Useful information: The number of ways to distribute n objects between two bins such th

Chapter: 17 Problem: 17.116

Chemistry 12
At what point in the series HOnH(g) (n 5 1, 2, 3, . . .) does formation of the compound from the elements H2(g) and O2(g) become nonspontaneous?

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