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All Textbook Solutions for Chemistry: An Atoms First Approach

Consider the titration of 100.0 mL of 0.200 M HONH2 by 0.100 M HCI. (Kb for HONH2 = 1.1 108.) a. Calculate the pH after 0.0 mL of HCl has been added. b. Calculate the pH after 25.0 mL of HCl has been added. c. Calculate the pH after 70.0 mL of HCl has been added. d. Calculate the pH at the equivalence point. e. Calculate the pH after 300.0 mL of HCl has been added. f. At what volume of HCl added does the pH = 6.04?107CWP 108CP A buffer is made using 45.0 mL of 0.750 M HC3H5O2 (Ka = 1.3 105) and 55.0 mL of 0.700 M NaC3H5O2. What volume of 0.10 M NaOH must be added to change the pH of the original buffer solution by 2.5%?A 0.400-M solution of ammonia was titrated with hydrochloric acid to the equivalence point, where the total volume was 1.50 times the original volume. At what pH does the equivalence point occur?111CP Consider a solution formed by mixing 50.0 mL of 0.100 M H2SO4, 30.0 mL of 0.100 M HOCI, 25.0 mL of 0.200 M NaOH, 25.0 mL of 0.100 M Ba(OH)2, and 10.0 mL of 0.150 M KOH. Calculate the pH of this solution.When a diprotic acid, H2A, is titrated with NaOH, the protons on the diprotic acid are generally removed one at a time, resulting in a pH curve that has the following generic shape: a. Notice that the plot has essentially two titration curves. If the first equivalence point occurs at 100.0 mL NaOH added, what volume of NaOH added corresponds to the second equivalence point? b. For the following volumes of NaOH added, list the major species present after the OH reacts completely. i. 0 mL NaOH added ii. between 0 and 100.0 mL NaOH added iii. 100.0 mL NaOH added iv. between 100.0 and 200.0 mL NaOH added v. 200.0 mL NaOH added vi. after 200.0 mL NaOH added c. If the pH at 50.0 mL NaOH added is 4.0, and the pH at 150.0 mL NaOH added is 8.0, determine the values Ka1, and Ka2 for the diprotic acid.Consider the following two acids: In two separate experiments the pH was measured during the titration of 5.00 mmol of each acid with 0.200 M NaOH. Each experiment showed only one stoichiometric point when the data were plotted. In one experiment the stoichiometric point was at 25.00 mL added NaOH, and in the other experiment the stoichiometric point was at 50.00 mL NaOH. Explain these results. (See Exercise 113.)The titration of Na2CO3 with HCl bas the following qualitative profile: a. Identify the major species in solution at points AF. b. Calculate the pH at the halfway points to equivalence, B and D. (Hint: Refer to Exercise 113.)116CP A few drops of each of the indicators shown in the accompanying table were placed in separate portions of a 1.0-M solution of a weak acid, HX. The results are shown in the last column of the table. What is the approximate pH of the solution containing HX? Calculate the approximate value of Ka for HX. Indicator Color of Hln Color of ln pKa of Hln Color of 1.0 M HX Bromphenol blue Yellow Blue 4.0 Blue Bromcresol purple Yellow Purple 6.0 Yellow Bromcresol green Yellow Blue 4.8 Green Alizarin Yellow Red 6.5 Yellow Malonic acid (HO2CCH2CO2H) is a diprotic acid. In the titration of malonic acid w ith NaOH, stoichiometric points occur at pH = 3.9 and 8.8. A 25.00-mL sample of malonic acid of unknown concentration is titrated with 0.0984 M NaOH, requiring 31.50 mL of the NaOH solution to reach the phenolphthalein end point. Calculate the concentration of the initial malonic acid solution. (Sec Exercise 113.)A buffer solution is prepared by mixing 75.0 mL of 0.275 M fluorobenzoic acid (C7H5O2F) with 55.0 mL of 0.472 M sodium fluorobenzoate. The pKa of this weak acid is 2.90. What is the pH of the buffer solution?A 10.00-g sample of the ionic compound NaA, where A is the anion of a weak acid, was dissolved in enough water to make 100.0 mL of solution and was then titrated with 0.100 M HCl. After 500.0 mL HCl was added, the pH was 5.00. The experimenter found that 1.00 L of 0.100 M HCl was required to reach the stoichiometric point of the titration. a. What is the molar mass of NaA? b. Calculate the pH of the solution at the stoichiometric point of the titration.121IP 122MP To what reaction does the solubility product constant, Ksp, refer? Table 15-1 lists Ksp values for several ionic solids. For any of these ionic compounds, you should be able to calculate the solubility. What is the solubility of a salt, and what procedures do you follow to calculate the solubility of a salt? How would you calculate the Ksp value for a salt given the solubility?2RQ 3RQ 4RQ 5RQ 6RQ 7RQ 8RQ 9RQ 10RQ 1ALQ 2ALQ 3ALQ A friend tells you: The constant Ksp of a salt is called the solubility product constant and is calculated from the concentrations of ions in the solution. Thus, if salt A dissolves to a greater extent than salt B, salt A must have a higher Ksp than salt B. Do you agree with your friend? Explain.5ALQ 6ALQ 7ALQ For which of the following is the Ksp value of the ionic compound the largest? The smallest? Explain your answer.Ag2S(s) has a larger molar solubility than CuS even though Ag2S has the smaller Ksp value. Explain how this is possible.10Q 11Q When Na3PO4(aq) is added to a solution containing a metal ion and a precipitate forms, the precipitate generally could be one of two possibilities. What are the two possibilities?The common ion effect for ionic solids (salts) is to significantly decrease the solubility of the ionic compound in water. Explain the common ion effect.14Q 15Q The stepwise formation constants for a complex ion usually have values much greater than 1. What is the significance of this?17Q 18Q Write balanced equations for the dissolution reactions and the corresponding solubility product expressions for each of the following solids. a. AgC2H3O2 b. Al(OH)3 c. Ca3(PO4)2 Write balanced equations for the dissolution reactions and the corresponding solubility product expressions for each of the following solids. a. Ag2CO3 b. Ce(IO3)3 c. BaF2 21E Use the following data to calculate the Ksp value for each solid. a. The solubility of Pb3(PO4) is 6.2 1012 mol/L. b. The solubility of Li2CO3 is 7.4 102 mol/L.Approximately 0.14 g nickel(II) hydroxide, Ni(OH)2(s), dissolves per liter of water at 20C. Calculate Ksp for Ni(OH)2(s) at this temperature.The solubility of the ionic compound M2X3, having a molar mass of 288 g/mol, is 3.60 107 g/L. Calculate the Ksp of the compound.25E 26E Calculate the solubility of each of the following compounds in moles per liter. Ignore any acidbase properties. a. Ag3PO4, Ksp = 1.8 1018 b. CaCO3, Ksp = 8.7 109 c. Hg2Cl2, Ksp = 1.1 1018 (Hg22+ is the cation in solution.)28E Cream of tartar, a common ingredient in cooking, is the common name for potassium bitartrate (abbreviated KBT, molar mass = 188.2 g/mol). Historically, KBT was a crystalline solid that formed on the casks of wine barrels during the fermentation process. Calculate the maximum mass of KBT that can dissolve in 250.0 mL of solution to make a saturated solution. The Ksp value for KBT is 3.8 104.30E 31E Calculate the molar solubility of Cd(OH)2, Ksp = 5.9 1011.Calculate the molar solubility of Al(OH)3, Ksp = 2 1032.Calculate the molar solubility of Co(OH)3, Ksp = 2.5 1043.35E For each of the following pairs of solids, determine which solid has the smallest molar solubility. a. FeC2O4, Ksp = 2.1 107, or Cu(IO4)2, Ksp = 1.4 107 b. Ag2CO3, Ksp = 8.1 1012, or Mn(OH)2, Ksp = 2 1013 Calculate the solubility (in moles per liter) of Fe(OH)3 (Ksp = 4 1038) in each of the following. a. water b. a solution buffered at pH = 5.0 c. a solution buffered at pH = 11.0 Calculate the solubility of Co(OH)2(s) (Ksp = 2.5 1016) in a buffered solution with a pH of 11.00.The Ksp for silver sulfate (Ag2SO4) is 1.2 105. Calculate the solubility of silver sulfate in each of the following. a. water b. 0.10 M AgNO3 c. 0.20 M K2SO4.40E 41E 42E 43E The solubility of Pb(IO3)(s) in a 0.10-M KIO3 solution is 2.6 1011 mol/L. Calculate Ksp for Pb(IO3)2(s).45E For which salt in each of the following groups will the solubility depend on pH? a. AgF, AgCl, AgBr b. Pb(OH)2, PbCl2 c. Sr(NO3)2, Sr(NO2)2 d. Ni(N03)2, Ni(CN)2 What mass of ZnS (Ksp = 2.5 1022) will dissolve in 300.0 mL of 0.050 M Zn(NO3)2? Ignore the basic properties of S2.The concentration of Mg2+ in seawater is 0.052 M. At what pH will 99% of the Mg2+ be precipitated as the hydroxide salt? [Ksp for Mg(OH)2 = 8.9 1012.]Will a precipitate form when 100.0 mL of 4.0 104 M Mg(NO3)2 is added to 100.0 mL of 2.0 104 M NaOH?A solution contains 1.0 105 M Ag+ and 2.0 106 M CN. Will AgCN(s) precipitate? (Ksp for AgCN(s) is 2.2 1012.A solution is prepared by mixing 100.0 mL of 1.0 102 M Pb(NO3)2 and 100.0 mL of 1.0 103 M NaF. Will PbF2(s) (Ksp = 4 108) precipitate?52E Calculate the final concentrations of K+(aq), C2O42(aq), Ba2+(aq), and Br (aq) in a solution prepared by adding 0.100 L of 0.200 M K2C2O4 to 0.150 L of 0.250 M BaBr2. (For BaC2O4, Ksp = 2.3 108.)54E A 50.0-mL sample of 0.00200 M AgNO3 is added to 50.0 mL of 0.0100 M NaIO3. What is the equilibrium concentration of Ag+ in solution? (Ksp for AgIO3 is 3.0 108.)56E A solution contains 1.0 105 M Na3PO4. What is the minimum concentration of AgNO3 that would cause precipitation of solid Ag3PO4 (Ksp = 1.8 1018)The Ksp of Al(OH)3 is 2 1032. At what pH will a 0.2-M Al3+ solution begin to show precipitation of Al(OH)3?A solution is 1 104 M in NaF, Na2S, and Na3PO4. What would be the order of precipitation as a source of Pb2+ is added gradually to the solution? The relevant Ksp values are Ksp(PbF2) = 4 108, Ksp(PbS) = 7 1029, and Ksp[Pb3(PO4)2] = 1 1054.A solution contains 0.25 M Ni(NO3)2 and 0.25 M Cu(NO3)2. Can the metal ions be separated by slowly adding Na2CO3? Assume that for successful separation 99% of the metal ion must be precipitated before the other metal ion begins to precipitate, and assume no volume change on addition of Na2CO3.Write equations for the stepwise formation of each of the following complex ions. a. Ni(CN)42 b. V(C2O4)33 Write equations for the stepwise formation of each of the following complex ions. a. CoF63 b. Zn(NH3)42+In the presence of CN, Fe3+ forms the complex ion Fe(CN)63. The equilibrium concentrations of Fe3+ and Fe(CN)63 are 8.5 1040 M and 1.5 103 M, respectively, in a 0.11-M KCN solution. Calculate the value for the overall formation constant of Fe(CN)63. Fe3+(aq)+6CN(aq)Fe(CN)63(aq)Koverall=?In the presence of NH3, Cu2+ forms the complex ion Cu(NH3)42+. If the equilibrium concentrations of Cu2+ and Cu(NH3)42+ are 1.8 1017 M and 1.0 103 M, respectively, in a 1.5-M NH3 solution, calculate the value for the overall formation constant of Cu(NH3)42+. Cu2+(aq)+4NH3(aq)Cu(NH3)42+(aq)Koverall=?65E 66E The overall formation constant for HgI42 is 1.0 1030. That is, 1.01030=[HgI42][Hg2+][I]4 What is the concentration of Hg2+ in 500.0 mL of a solution that was originally 0.010 M Hg2+ and 0.78 M I? The reaction is Hg2+(aq)+4I(aq)HgI42(aq)68E A solution is formed by mixing 50.0 mL of 10.0 M NaX with 50.0 mL of 2.0 103 M CuNO3. Assume that Cu+ forms complex ions with X as follows: Cu+(aq)+X(aq)CuX(aq)K1=1.0102CuX(aq)+X(aq)CuX2(aq)K2=1.0104CuX2(aq)+X(aq)CuX32(aq)K3=1.0103 with an overall reaction Cu+(aq)+3X(aq)CuX32(aq)K=1.0109 Calculate the following concentrations at equilibrium. a. Cux32 b. CuX2 c. Cu+A solution is prepared by mixing 100.0 mL of 1.0 104 M Be(NO3)2 and 100.0 mL of 8.0 M NaF. Be2+(aq)+F(aq)BeF+(aq)K1=7.9104BeF+(aq)+F(aq)BeF2(aq)K2=5.8103BeF2(aq)+F(aq)BeF3(aq)K3=6.1102BeF3(aq)+F(aq)BeF42(aq)K4=2.7101 Calculate the equilibrium concentrations of F, Be2+, BeF+, BeF2, BeF3, and BeF42 in this solution.a. Calculate the molar solubility of AgI in pure water. Ksp for AgI is 1.5 1016. b. Calculate the molar solubility of AgI in 3.0 M NH3. The overall formation constant for Ag(NH3)2+ is 1.7 107. c. Compare the calculated solubilities from parts a and b. Explain any differences.Solutions of sodium thiosulfate are used to dissolve unexposed AgBr (Ksp = 5.0 1013) in the developing process for black-and-white film. What mass of AgBr can dissolve in 1.00 L of 0.500 M Na2S2O3? Ag+ reacts with S2O32 to form a complex ion: Ag+(aq)+2S2O32(aq)Ag(S2O3)23(aq)K=2.91013 Kf for the complex ion Ag(NH3)2+ is 1.7 107. Ksp for AgCl is 1.6 1010. Calculate the molar solubility of AgCl in 1.0 M NH3.74E 75E The solubility of copper(II) hydroxide in water can be increased by adding either the base NH3 or the acid HNO3. Explain. Would added NH3 or HNO3 have the same effect on the solubility of silver acetate or silver chloride? Explain.A solution contains 0.018 mole each of I, Br, and Cl. When the solution is mixed with 200. mL of 0.24 M AgNO3, what mass of AgCl(s) precipitates out, and what is [Ag+]? Assume no volume change. AgI:Ksp=1.51016AgBr:Ksp=5.01013AgCl:Ksp=1.61010 78AE Tooth enamel is composed of the mineral hydroxyapatite. The Ksp of hydroxyapatite, Ca5(PO4)3OH, is 6.8 1037. Calculate the solubility of hydroxyapatite in pure water in moles per liter. How is the solubility of hydroxyapatite affected by adding acid? When hydroxyapatite is treated with fluoride, the mineral fluorapatite, Ca5(PO4)3F, forms. The Ksp of this substance is 1 1060. Calculate the solubility of fluorapatite in water. How do these calculations provide a rationale for the fluoridation of drinking water?80AE What mass of Ca(NO3)2 must be added to 1.0 L of a 1.0-M HF solution to begin precipitation of CaF2(s)? For CaF2, Ksp = 4.0 1011 and Ka for HF = 7.2 104. Assume no volume change on addition of Ca(NO3)2(s).Calculate the mass of manganese hydroxide present in 1300 mL of a saturated manganese hydroxide solution. For Mn(OH)2, Ksp = 2.0 1013.83AE The active ingredient of Pepto-Bismol is the compound bismuth subsalicylate, which undergoes the following dissociation when added to water: C7H5BiO4(s)+H2O(l)C7H4O32(aq)+Bi3+(aq)+OH(aq)K=? If the maximum amount of bismuth subsalicylate that reacts by this reaction is 3.2 1019 mol/L, calculate the equilibrium constant for the preceding reaction.85AE The equilibrium constant for the following reaction is 1.0 1023: Cr3+(aq)+H2EDTA2(aq)CrEDTA(aq)+2H+(aq) EDTA is used as a complexing agent in chemical analysis. Solutions of EDTA, usually containing the disodium salt Na2H2EDTA, are used to treat heavy metal poisoning. Calculate [Cr3+] at equilibrium in a solution originally 0.0010 M in Cr3+ and 0.050 M in H2EDTA2 and buffered at pH = 6.00.Calculate the concentration of Pb2+ in each of the following. a. a saturated solution of Pb(OH)2, Ksp = 1.2 1015 b. a saturated solution of Pb(OH)2 buffered at pH = 13.00 c. Ethylenediaminetetraacetate (EDTA4) is used as a complexing agent in chemical analysis and has the following structure: Solutions of EDTA4 are used to treat heavy metal poisoning by removing the heavy metal in the form of a soluble complex ion. The reaction of EDTA4 with Pb2+ is Pb2+(aq)+EDTA4(aq)PbEDTA2(aq)K=1.11018 Consider a solution with 0.010 mole of Pb(NO3)2 added to 1.0 L of an aqueous solution buffered at pH = 13.00 and containing 0.050 M Na4.EDTA. Does Pb(OH)2 precipitate from this solution?Will a precipitate of Cd(OH)2 form if 1.0 mL of 1.0 M Cd(NO3)2 is added to 1.0 L of 5.0 M NH3? Cd2+(aq)+4NH3(aq)Cd(NH3)42+(aq)K=1.0107Cd(OH)2(s)Cd2+(aq)+2OH(aq)Ksp=5.91015 89AE Describe how you could separate the ions in each of the following groups by selective precipitation. a. Ag+, Mg2+, Cu2+ b. Pb2+, Ca2+, Fe2+ c. Pb2+, Bi3+91AE 92AE 93CWP 94CWP 95CWP The solubility of Pb(IO3)2(s) in a 7.2 102-M KIO3 solution is 6.0 109 mol/L. Calculate the Ksp value for Pb(IO3)2(s).A 50.0-mL sample of 0.0413 M AgNO3(aq) is added to 50.0 mL of 0.100 M NaIO3(aq). Calculate the [Ag+] at equilibrium in the resulting solution. [Ksp for AgIO3(s) = 3.17 108.]98CWP 99CP Consider a solution made by mixing 500.0 mL of 4.0 M NH3 and 500.0 mL of 0.40 M AgNO3. Ag+ reacts with NH3 to form AgNH3+ and Ag(NH3)2+: Ag+(aq)+NH3(aq)AgNH3+(aq)K1=2.1103AgNH3+(aq)+NH3(aq)Ag(NH3)2+(aq)K2=8.2103 Determine the concentration of all species in solution.a. Calculate the molar solubility of AgBr in pure water. Ksp for AgBr is 5.0 1013. b. Calculate the molar solubility of AgBr in 3.0 M NH3. The overall formation constant for Ag(NH3)2+ is 1.7 107, that is, Ag+(aq)+2NH3(aq)Ag(NH3)2+(aq)K=1.7107. c. Compare the calculated solubilities from parts a and b. Explain any differences. d. What mass of AgBr will dissolve in 250.0 mL of 3.0 M NH3? e. What effect does adding HNO3 have on the solubilities calculated in parts a and b?102CP 103CP Calcium oxalate (CaC2O4) is relatively insoluble in water (Ksp = 2 109). However, calcium oxalate is more soluble in acidic solution. How much more soluble is calcium oxalate in 0.10 M H+ than in pure water? In pure water, ignore the basic properties of C2O42.What is the maximum possible concentration of Ni2+ ion in water at 25C that is saturated with 0.10 M H2S and maintained at pH 3.0 with HCl?A mixture contains 1.0 103 M Cu2+ and 1.0 103 M Mn2+ and is saturated with 0.10 M H2S. Determine a pH where CuS precipitates but MnS does not precipitate. Ksp for CuS = 8.5 1045 and Ksp for MnS = 2.3 1013.Sodium tripolyphosphate (Na5P3O10) is used in many synthetic detergents. Its major effect is to soften the water by complexing Mg2+ and Ca2+ ions. It also increases the efficiency of surfactants, or wetting agents that lower a liquids surface tension. The K value for the formation of MgP3O103 is 4.0 108 The reaction isMg2+(aq)+P3O105(aq)MgP3O103(aq). Calculate the concentration of Mg2+ in a solution that was originally 50. ppm Mg2+ (50. mg/L of solution) after 40. g Na5P3O10 is added to 1.0 L of the solution.You add an excess of solid MX in 250g water. You measure the freezing point and find it to be 0.028C. What is the Ksp of the solid? Assume the density of the solution is 1.0 g/cm3.a. Calculate the molar solubility of SrF2 in water, ignoring the basic properties of F. (For SrF2, Ksp = 7.9 1010.) b. Would the measured molar solubility of SrF2 be greater than or less than the value calculated in part a? Explain. c. Calculate the molar solubility of SrF2 in a solution buffered at pH = 2.00. (Ka for HF is 7.2 104.)110IP 111IP 112IP Aluminum ions react with the hydroxide ion to form the precipitate Al(OH)3(s), but can also react to form the soluble complex ion Al(OH)4. In terms of solubility, Al(OH)3(s) will be more soluble in very acidic solutions as well as more soluble in very basic solutions. a. Write equations for the reactions that occur to increase the solubility of Al(OH)3(s) in very acidic solutions and in very basic solutions. b. Lets study the pH dependence of the solubility of Al(OH)3(s) in more detail. Show that the solubility of Al(OH)3, as a function of [H+], obeys the equation S=[H+]3Ksp/Kw3+KKw/[H+] where S = solubility = [Al3+] + [Al(OH)4] and K is the equilibrium constant for Al(OH)3(s)+OH(aq)Al(OH)4(aq) c. The value of K is 40.0 and Ksp for Al(OH)3 is 2 1032. Plot the solubility of Al(OH)3 in the pH range 412.Define the following: a. spontaneous process b. entropy c. positional probability d. system e. surroundings f. universe What is the second law of thermodynamics? For any process, there are four possible sign combinations for Ssys and Ssurr. Which sign combination(s) always give a spontaneous process? Which sign combination(s) always give a non-spontaneous process? Which sign combination(s) may or may not give a spontaneous process?3RQ 4RQ 5RQ What is the standard free energy change, G, for a reaction? What is the standard free energy of formation, Gf for a substance? How are Gf values used to calculate Grxn? How can you use Hesss law to calculate Grxn? How can you use H and S values to calculate Grxn? Of the functions H, S, and G, which depends most strongly on temperature? When G is calculated at temperatures other than 25Cwhat assumptions are generally made concerning H and S?If you calculate a value for G for a reaction using the values of Gf in Appendix 4 and get a negative number, is it correct to say that the reaction is always spontaneous? Why or why not? Free energy changes also depend on concentration. For gases, how is G related to the pressure of the gas? What are standard pressures for gases and standard concentrations for solutes? How do you calculate G for a reaction at nonstandard conditions? The equation to determine G at nonstandard conditions has Q in it: What is Q? A reaction is spontaneous as long as G is negative; that is, reactions always proceed as long as the products have a lower free energy than the reactants. What is so special about equilibrium? Why dont reactions move away from equilibrium?Consider the equation G = G + RT ln(Q). What is the value of G for a reaction at equilibrium? What does Q equal at equilibrium? At equilibrium, the previous equation reduces to G = RT ln(K). When G 0, what does it indicate about K? When G 0, what does it indicate about K? When t G = 0, what does it indicate about K? G predicts spontaneity for a reaction, whereas G predicts the equilibrium position. Explain what this statement means. Under what conditions can you use G to determine the spontaneity of a reaction?Even if G is negative, the reaction may not occur. Explain the interplay between the thermodynamics and the kinetics of a reaction. High temperatures are favorable to a reaction kinetically but may be unfavorable to a reaction thermodynamically. Explain.10RQ For the process A(l) A(g), which direction is favored by changes in energy probability? Positional probability? Explain your answers. If you wanted to favor the process as written, would you raise or lower the temperature of the system? Explain.2ALQ Gas A2 reacts with gas B2 to form gas AB at a constant temperature. The bond energy of AB is much greater than that of either reactant. What can be said about the sign of H? SSurr? S? Explain how potential energy changes for this process. Explain how random kinetic energy changes during the process.4ALQ 5ALQ 6ALQ Predict the sign of S for each of the following and explain. a. the evaporation of alcohol b. the freezing of water c. compressing an ideal gas at constant temperature d. dissolving NaCl in water Is Ssurr favorable or unfavorable for exothermic reactions? Endothermic reactions? Explain.At 1 atm, liquid water is heated above 100C. For this process, which of the following choices (iiv) is correct for Ssurr? S? Suniv? Explain each answer. i. greater than zero ii. less than zero iii. equal to zero iv. cannot be determined 10ALQ The synthesis of glucose directly from CO2 and H2O and the synthesis of proteins directly from amino acids are both non-spontaneous processes under standard conditions. Yet it is necessary for these to occur for life to exist. In light of the second law of thermodynamics, how can life exist?When the environment is contaminated by a toxic or potentially toxic substance (for example, from a chemical spill or the use of insecticides). the substance tends to disperse. How is this consistent with the second law of thermodynamics? In terms of the second Jaw. which requires the least work: cleaning the environment after it has been contaminated or trying to prevent the contamination before it occurs? Explain.Entropy has been described as times arrow. Interpret this view of entropy.14Q A mixture of hydrogen gas and chlorine gas remains unreacted until it is exposed to ultraviolet light from a burning magnesium strip. Then the following reaction occurs very rapidly: H2(g)+Cl2(g)2HCl(g) Explain.Consider the following potential energy plots: a. Rank the reactions from fastest to slowest and explain your answer. If any reactions have equal rates, explain why. b. Label the reactions as endothermic or exothermic, and support your answer. c. Rank the exothermic reactions from greatest to least change in potential energy. and support your answer.17Q Given the following illustration, what can be said about the sign of S for the process of solid NaCl dissolving in water? What can be said about H for this process?The third law of thermodynamics states that the entropy of a perfect crystal at 0 K is zero. In Appendix 4, F(aq), OH(aq), and S2(aq) all have negative standard entropy values. How can S values be less than zero?20Q 21Q 22Q Monochloroethane (C2H5Cl) can be produced by the direct reaction of ethane gas (C2H6) with chlorine gas or by the reaction of ethylene gas (C2H4) with hydrogen chloride gas. The second reaction gives almost a 100% yield of pure C2H5Cl at a rapid rate without catalysis. The first method requires light as an energy source or the reaction would not occur. Yet G for the first reaction is considerably more negative than G for the second reaction. Explain how this can be so.24Q Which of the following processes are spontaneous? a. Salt dissolves in H2O. b. A clear solution becomes a uniform color after a few drops of dye are added. c. Iron rusts. d. You clean your bedroom.Which of the following processes are spontaneous? a. A house is built. b. A satellite is launched into orbit. c. A satellite falls back to the earth. d. The kitchen gets cluttered.27E Consider the following illustration of six molecules of gas in a two-bulbed flask. a. What is the most likely arrangement of molecules? How many microstates are there for this arrangement? b. Determine the probability of finding the gas in its most likely arrangement.Consider the following energy levels, each capable of holding two particles: Draw all the possible arrangements of the two identical particles (represented by X) in the three energy levels. What total energy is most likely, that is, occurs the greatest number of times? Assume that the particles are indistinguishable from each other.30E Choose the substance with the larger positional probability in each case. a. 1 mole of H2 (at STP) or 1 mole of H2 (at l00C, 0.5 atm) b. 1 mole of N2 (at STP) or 1 mole of N2 (at l00 K, 2.0 atm) c. 1 mole of H2O(s) (at 0C) or 1 mole of H2O(l) (at 20C)Which of the following involve an increase in the entropy of the system? a. melting of a solid b. sublimation c. freezing d. mixing e. separation f. boiling Predict the sign of Ssurr for the following processes. a. H2O(l) H2O(g) b. I2(g) I2(s)34E Given the values of H and S, which of the following changes will be spontaneous at constant T and p? a. H = + 25 kJ, S = + 5.0 J/K, T = 300. K b. H = + 25 kJ, S = + 100. J/K, T = 300. K c. H = 10. kJ, S = + 5.0 J/K, T= 298 K d. H = 10.kJ, S =40.J/K, T = 200.K At what temperatures will the following processes be spontaneous? a. H = 18 kJ and S = 60. J/K b. H = +18 kJ and S = + 60. J/K c. H = +18 kJ and S = 60. J/K d. H = 18 kJ and S = +60. J/K Ethanethiol (C2H5SH; also called ethyl mercaptan) is commonly added to natural gas to provide the rotten egg smell of a gas leak. The boiling point of ethanethiol is 35C and its heat of vaporization is 27.5 kJ/mol. What is the entropy of vaporization for this substance?For mercury, the enthalpy of vaporization is 58.51 kJ/mol and the entropy of vaporization is 92.92 J/K mol. What is the normal boiling point of mercury?For ammonia (NH3), the enthalpy of fusion is 5.65 kJ/mol and the entropy of fusion is 28.9 J/K mol. a. Will NH3(s) spontaneously melt at 200. K? b. What is the approximate melting point of ammonia?The enthalpy of vaporization of ethanol is 38.7 kJ/mol at its boiling point (78C). Determine Ssys, Ssurr, and Suniv when 1.00 mole of ethanol is vaporized at 78C and 1.00 atm.Predict the sign of S for each of the following changes. Assume all equations are balanced. a. b. c. d.42E 43E For each of the following pairs, which substance has the greater value of S? a. N2O (at 0 K) or He (at 10 K) b. N2O(g) (at 1 atm, 25C) or He(g) (at 1 atm, 25C) c. NH3(s) (at 196 K) NH3(l) (at 196 K)Predict the sign of S and then calculate S for each of the following reactions. a. 2H2S (g) + SO2(g) 3Srhommbic(s) + 2H2O(g) b. 2SO3 (g) 2SO2(g) + O2(g) c. Fe2O3(s) + 3H2(g) 2Fe(s) + 3H2O (g)Predict the sign of S and then calculate S for each of the following reactions. a. H2(g) + 12O2(g) H2O(l) b. 2CH3OH(g) + 3O2(g) 2CO2(g) + 4H2O(g) c. HCl(g) H+(aq) + Cl (aq)47E 48E 49E Two crystalline forms of white phosphorus are known. Both forms contain P4 molecules, but the molecules are packed together in different ways. The form is always obtained when the liquid freezes. However, below 76.9C, the form spontaneously converts to the form: P4(s,)P4(s,) a. Predict the signs of H and S for this process. b. Predict which form of phosphorus has the more ordered crystalline structure (has the smaller positional probability).Consider the reaction 2O(g)O2(g) a. Predict the signs of H and S. b. Would the reaction be more spontaneous at high or low temperatures?52E 53E The major industrial use of hydrogen is in the production of ammonia by the Haber process: 3H2(g)+N2(g)2NH3(g) a. Using data from Appendix 4, calculate H, S, and G for the Haber process reaction. b. Is the reaction spontaneous at standard conditions? c. At what temperatures is the reaction spontaneous at standard conditions? Assume H and S do not depend on temperature.55E At 100C and 1.00 atm, H = 40.6 kJ/mol for the vaporization of water. Estimate G for the vaporization of water at 90.C and 110.C. Assume H and S at 100.C and 1.00 atm do not depend on temperature.57E 58E 59E 60E Consider the reaction Fe2O3(s)+3H2(g)2Fe(s)+3H2O(g) a. Use Gf values in Appendix 4 to calculate G for this reaction. b. Is this reaction spontaneous under standard conditions at 298 K? c. The value of H for this reaction is 100. kJ. At what temperatures is this reaction spontaneous at standard conditions? Assume that H and S do not depend on temperature.Consider the reaction 2POCl3(g)2PCl3(g)+O2(g) a. Calculate G for this reaction. The Gfvalues for POCI3(g) and PCI3(g) are 502 kJ/mol and 270. kJ/mol, respectively. b. Is this reaction spontaneous under standard conditions at 298 K? c. The value of S for this reaction is 179 J/K mol. At what temperatures is this reaction spontaneous at standard conditions? Assume that H and S do not depend on temperature.63E Consider two reactions for the production of ethanol: C2H4(g)+H2O(g)CH3CH2OH(l)C2H6(g)+H2O(g)CH3CH2OH(l)+H2(g) Which would be the more thermodynamically feasible at standard conditions? Why?65E 66E Consider the reaction 2NO2(g)N2O4(g) For each of the following mixtures of reactants and products at 25C, predict the direction in which the reaction will shift to reach equilibrium. a. PNO2=PN2O4=1.0atm b. PNO2=0.21atm,PN2O4=0.50atm c. PNO2=0.29atm,PN2O4=1.6atm 68E One of the reactions that destroys ozone in the upper atmosphere is NO(g)+O3(g)NO2(g)+O2(g) Using data from Appendix 4, calculate G and K (at 298 K) for this reaction.Hydrogen sulfide can be removed from natural gas by the reaction 2H2S(g)+SO2(g)3S(s)+2H2O(g) Calculate G and K (at 298 K) for this reaction. Would this reaction be favored at a high or low temperature?Consider the following reaction at 25.0C: 2NO2(g)N2O4(g) The values of H and S are 58.03 kJ/mol and 176.6 J/K mol, respectively. Calculate the value of K at 25.0C. Assuming H and S are temperature independent, estimate the value of K at 100.0C.The standard free energies of formation and the standard enthalpies of formation at 298 K for difluoroacetylene (C2F2) and hexafluorobenzene (C6F6) are Gfo(KJ/mol) Hfo(KJ/mol) C2F2(g) 191.2 241.3 Hexane 78.2 132.8 For the following reaction: C6F6(g)3C2F2(g) a. calculate S at 298 K. b. calculate K at 298 K. c. estimate K at 3000. K, assuming H and S do not depend on temperature.Calculate G forH2O(g)+12O2(g)H2O2(g) at 600. K, using the following data: H2(g)+O2(g)H2O2(g)K=2.3106at600.K2H2(g)+O2(g)2H2O(g)K=1.81037at600.K The Ostwald process for the commercial production of nitric acid involves three steps: 4NH3(g)+5O2(g)825CPt4NO(g)+6H2O(g)2NO(g)+O2(g)2NO2(g)3NO2(g)+H2O(l)2HNO3(l)+NO(g) a. Calculate H, S,G and K (at 298 K) for each of the three steps in the Ostwald process (see Appendix 4). b. Calculate the equilibrium constant for the first step at 825C, assuming H and S do not depend on temperature. c. Is there a thermodynamic reason for the high temperature in the first step, assuming standard conditions?Cells use the hydrolysis of adenosine triphosphate, abbreviated as ATP, as a source of energy. Symbolically, this reaction can be written as ATP(aq)+H2O(l)ADP(aq)+H2PO4(aq) where ADP represents adenosine diphosphate. For this reaction, G =30.5 kJ/mol. a. Calculate K at 25C. b. If all the free energy from the metabolism of glucose C6H12O6(s)+6O2(g)6CO2(g)+6H2O(l) goes into forming ATP from ADP, how many ATP molecules can be produced for every molecule of glucose?One reaction that occurs in human metabolism is For this reaction G= 14 kJ at 25c. a. Calculate K for this reaction at 25C. b. In a living cell this reaction is coupled with the hydrolysis of ATP. (See Exercise 75.) Calculate G and K at 25C for the following reaction: Glutamicacid(aq)+ATP(aq)+NH3(aq)Glutamine(aq)+ADP(aq)+H2PO4(aq)77E Consider the following reaction at 298 K: 2SO2(g)+O2(g)2SO3(g) An equilibrium mixture contains O2(g) and SO3(g) at partial pressures of 0.50 atm and 2.0 atm, respectively. Using data from Appendix 4, determine the equilibrium partial pressure of SO2 in the mixture. Will this reaction be most favored at a high or a low temperature, assuming standard conditions?79E The equilibrium constant K for the reaction 2CI(g)CI2(g) was measured as a function of temperature (Kelvin). A graph of In (K) versus 1/T for this reaction gives a straight line with a slope of 1.352 104 K and a y-intercept of 14.5 1. Determine the values of H and S for this reaction. See Exercise 79.81AE Some water is placed in a coffee-cup calorimeter. When 1.0 g of an ionic solid is added, the temperature of the solution increases from 21.5C to 24.2C as the solid dissolves. For the dissolving process, what are the signs for Ssys, Ssurr, and Suniv?Consider the following system at equilibrium at 25C: PCl3(g)+Cl(g)PCl5(g)G=92.50KJ What will happen to the ratio of partial pressure of PCl5 to partial pressure of PCI3 if the temperature is raised? Explain completely.Calculate the entropy change for the vaporization of liquid methane and liquid hexane using the following data. Boilling point (1atm) Hvap Methane 112K 8.20 KJ/mol Hexane 342K 28.9 KJ/mol Compare the molar volume of gaseous methane at 112 K with that of gaseous hexane at 342 K. How do the differences in molar volume affect the values of Svap for these liquids?As O2(l) is cooled at 1 atm, it freezes at 54.5 K to form solid I. At a lower temperature, solid I rearranges to solid II, which has a different crystal structure. Thermal measurements show that H for the I II phase transition is 743.1 J/mol, and S for the same transition is 17.0 J/K mol. At what temperature are solids 1 and II in equilibrium?86AE Using the following data, calculate the value of Ksp for Ba(NO3)2, one of the least soluble of the common nitrate salts. Species Gfo Ba2+(aq) 561 KJ/mol NO3(aq) 109 KJ/mol Ba(NO3)2(s) 797KJ/mol 88AE Carbon monoxide is toxic because it bonds much more strongly to the iron in hemoglobin (Hgb) than does O2. Consider the following reactions and approximate standard free energy changes: Hgb+O2HgbO2G=70KJHgb+COHgbCOG=80KJ Using these data, estimate the equilibrium constant value at 25C for the following reaction: HgbO2+COHgbCO+O2 90AE 91AE Use the equation in Exercise 79 to determine H and S for the autoionization of water: H2O(l)H+(aq)+OH-(aq) T(C) KW 0 1.141015 25 1.001014 35 2.091014 40. 2.921014 50. 5.471014 Consider the reaction Fe2O3(s)+3H2(g)2Fe(s)+3H2O(g) Assuming H and S do not depend on temperature, calculate the temperature where K = 1.00 for this reaction.Consider the following diagram of free energy (G) versus fraction of A reacted in terms of moles for the reaction 2A(g) B(g). Before any A has reacted, PA = 3.0 atm and PB = 0. Determine the sign of G and the value of Kp. for this reaction.95CWP For rubidium Hvapo=69.0KJ/mol at 686C, its boiling point. Calculate S, q, w, and E for the vaporization of 1.00 mole of rubidium at 686C and 1.00 atm pressure.Given the thermodynamic data below, calculate S and Ssurr for the following reaction at 25C and 1 atm: XeF6(g)XeF4(s)+F2(g) Hfo(KJ/mol) S(J/K mol) XeF6(g) -294 300. XeF4(s) -251 146 F2(g) 0 203 98CWP 99CWP Consider the dissociation of a weak acid HA (Ka = 4.5 103) in water: HA(aq)H+(aq)+A-(aq) Calculate G for this reaction at 25C.101CWP The equilibrium constant for a certain reaction increases by a factor of 6.67 when the temperature is increased from 300.0 K to 350.0 K. Calculate the standard change in enthalpy (H) for this reaction (assuming H is temperature-independent).For the following reactions at constant pressure, predict if HE,HE,orH=E a. 2HF(g)H2(g)+F2(g) b. N2(g)+3H2(g)2NH3(g) c. 4NH3(g)+5O2(g)4NO(g)+6H2O(g)The standard enthalpy of formation of H2O(l) at 298 K is 285.8 kJ/mol. Calculate the change in internal energy for the following process at 298 K and 1 atm: H2O(l)H2(g)+12O2(g)E=? (Hint: Using the ideal gas equation, derive an expression for work in terms of n, R, and T.)105CP Liquid water at 25C is introduced into an evacuated, insulated vessel. Identify the signs of the following thermodynamic functions for the process that occurs: H, S, Twater, Ssurr,, Suniv.Using data from Appendix 4, calculate H, G, and K (at 298 K) for the production of ozone from oxygen: 3O2(g)2O3(g) At 30 km above the surface of the earth, the temperature is about 230. K and the partial pressure of oxygen is about 1.0 103 atm. Estimate the partial pressure of ozone in equilibrium with oxygen at 30 km above the earth's surface. Is it reasonable to assume that the equilibrium between oxygen and ozone is maintained under these conditions? Explain.108CP 109CP 110CP 111CP 112CP If wet silver carbonate is dried in a stream of hot air. the air must have a certain concentration level of carbon dioxide to prevent silver carbonate from decomposing by the reaction Ag2CO3(s)Ag2O(s)+CO2(g) H for this reaction is 79.14 kJ/mol in the temperature range of 25 to 125C. Given that the partial pressure of carbon dioxide in equilibrium with pure solid silver carbonate is 6.23 103 torr at 25C, calculate the partial pressure of CO2 necessary to prevent decomposition ofAg2CO3 at 110C. (Hint: Manipulate the equation in Exercise 79.)Carbon tetrachloride (CCl4) and benzene (C6H6) form ideal solutions. Consider an equimolar solution of CCl4 and C6H6 at 25C. The vapor above the solution is collected and condensed. Using the following data, determine the composition in mole fraction of the condensed vapor. Substance Gfo C6H6(l) 124.50 kJ/mol C6H6(g) 129.66 kJ/mol CCI4(l) 65.21 kJ/mol CCI4,(g) 60.59 kJ/mol Sodium chloride is added to water (at 25C) until it is saturated. Calculate the Cl concentration in such a solution. Species G(kJ/mol) NaCl(s) 384 Na+(aq) 262 Cl(aq) 131 116CP 117CP 118IP 119IP 120IP Consider a sample containing 5.00 moles of a monatomic ideal gas that is taken from state A to state B by the following two pathways: For each step, assume that the external pressure is constant and equals the final pressure of the gas for that step. Calculate q, w, E and H for each step in kJ, and calculate overall values for each pathway. Explain how the overall values for the two pathways illustrate that E and H are state functions, whereas q and w are path functions. Hint: In a more rigorous study of thermochemistry, it can be shown that for an ideal gas: E=nCvTand H=nCpT where Cv is the molar heat capacity at constant volume and Cp is the molar heat capacity at constant pressure. In addition, for a monatomic ideal gas, Cv=32R andCp=52R , where R = 8.3145 J/K mol.Impure nickel, refined by smelting sulfide ores in a blast furnace, can be converted into metal from 99.90% to 99.99% purity by the Mond process. The primary reaction involved in the Mond process is Ni(s)+4CO(g)Ni(CO)4(g) a. Without referring to Appendix 4, predict the sign of S for the above reaction. Explain. b. The spontaneity of the above reaction is temperature-dependent. Predict the sign of Ssurr, for this reaction. Explain c. For Ni(CO)4(g), Hfo=607KJ/mol and S = 417 J/K mol at 298 K. Using these values and data in Appendix 4, calculate H and S for the above reaction. d. Calculate the temperature at which G = 0 (K = 1) for the above reaction, assuming that H and S do not depend on temperature. e. The first step of the Mood process involves equilibrating impure nickel with CO(g) and Ni(CO)4(g) at about 50C. The purpose of this step is to convert as much nickel as possible into the gas phase. Calculate the equilibrium constant for the above reaction at 50.C. f. In the second step of the Mood process, the gaseous Ni(CO)4 is isolated and heated to 227C. The purpose of this step is to deposit as much nickel as possible as pure solid (the reverse of the preceding reaction). Calculate the equilibrium constant for the preceding reaction at 227C. g. Why is temperature increased for the second step of the Mood process? h. The Mond process relies on the volatility of Ni(CO)4 for its success. Only pressures and temperatures at which Ni(CO)4 is a gas are useful. A recently developed variation of the Mood process carries out the first step at higher pressures and a temperature of l52C. Estimate the maximum pressure of Ni(CO)4(g) that can be attained before the gas will liquefy at 152C. The boiling point for Ni(CO)4 is 42C and the enthalpy of vaporization is 29.0 kJ/mol. [Hint: The phase change reaction and the corresponding equilibrium expression are Ni(CO)4(l)Ni(CO)4(g)K=PNi(CO)4 Ni(CO)4(g) will liquefy when the pressure of Ni(CO)4 is greater than the K value.]What is a half-reaction? Why must the number of electrons lost in the oxidation half-reaction equal the number of electrons gained in the reduction half-reaction? Summarize briefly the steps in the half-reaction method for balancing redox reactions. What two items must be balanced in a redox reaction (or any reaction)?Galvanic cells harness spontaneous oxidationreduction reactions to produce work by producing a current. They do so by controlling the flow of electrons from the species oxidized to the species reduced. How is a galvanic cell designed? What is in the cathode compartment? The anode compartment? What purpose do electrodes serve? Which way do electrons always flow in the wire connecting the two electrodes in a galvanic cell? Why is it necessary to use a salt bridge or a porous disk in a galvanic cell? Which way do cations flow in the salt bridge? Which way do the anions flow? What is a cell potential and what is a volt?Table 17-1 lists common half-reactions along with the standard reduction potential associated with each half-reaction. These standard reduction potentials are all relative to some standard. What is the standard (zero point)? lf is positive for a half-reaction, what does it mean? If is negative for a half-reaction, what does it mean? Which species in Table 17-1 is most easily reduced? Least easily reduced? The reverse of the half-reactions in Table 17-1 are the oxidation half-reactions. How are standard oxidation potentials determined? In Table 17-1, which species is the best reducing agent? The worst reducing agent? To determine the standard cell potential for a redox reaction, the standard reduction potential is added to the standard oxidation potential. What must be true about this sum if the cell is to be spontaneous (produce a galvanic cell)? Standard reduction and oxidation potentials are intensive. What does this mean? Summarize how line notation is used to describe galvanic cells.4RQ The Nernst equation allows determination of the cell potential for a galvanic cell at nonstandard conditions. Write out the Nernst equation. What are nonstandard conditions? What do , n, and Q stand for in the Nernst equation? What does the Nernst equation reduce to when a redox reaction is at equilibrium? What are the signs of G and when K 1? When K 1? When K = 1? Explain the following statement: determines spontaneity, while determines the equilibrium position. Under what conditions can you use to predict spontaneity?6RQ 7RQ 8RQ What characterizes an electrolytic cell? What is an ampere? When the current applied to an electrolytic cell is multiplied by the time in seconds, what quantity is determined? How is this quantity converted to moles of electrons required? How are moles of electrons required converted to moles of metal plated out? What does plating mean? How do you predict the cathode and the anode half-reactions in an electrolytic cell? Why is the electrolysis of molten salts much easier to predict in terms of what occurs at the anode and cathode than the electrolysis of aqueous dissolved salts? What is overvoltage?Sketch a galvanic cell, and explain how it works. Look at Figs. 17-1 and 17-2. Explain what is occurring in each container and why the cell in Fig. 17-2 works but the one in Fig. 17-1 does not.2ALQ 3ALQ 4ALQ Sketch a cell that forms iron metal from iron(II) while changing chromium metal to chromium(III). Calculate the voltage, show the electron flow, label the anode and cathode, and balance the overall cell equation.Which of the following is the best reducing agent: F2, H2, Na, Na+, F? Explain. Order as many of these species as possible from the best to the worst oxidizing agent. Why cant you order all of them? From Table 17-1 choose the species that is the best oxidizing agent. Choose the best reducing agent. Explain.7ALQ 8ALQ Explain why cell potentials are not multiplied by the coefficients in the balanced redox equation. (Use the relationship between G and cell potential to do this.)What is the difference between and ? When is equal to zero? When is equal to zero? (Consider regular galvanic cells as well as concentration cells.)11ALQ Look up the reduction potential for Fe3+ to Fe2+. Look up the reduction potential for Fe2+ to Fe. Finally, look up the reduction potential for Fe3+ to Fe. You should notice that adding the reduction potentials for the first two does not give the potential for the third. Why not? Show how you can use the first two potentials to calculate the third potential.13ALQ Is the following statement true or false? Concentration cells work because standard reduction potentials are dependent on concentration. Explain.15RORR Assign oxidation numbers to all the atoms in each of the following: a. HNO3 b. CuCl2 c. O2 d. H2O2 e. C6H12O6 f. Ag g. PbSO4 h. PbO2 i. Na2C2O4 j. CO2 k. (NH4)2Ce(SO4)3 l. Cr2O3 Specify which of the following equations represent oxidation reduction reactions, and indicate the oxidizing agent, the reducing agent, the species being oxidized, and the species being reduced. a. CH4(g)+H2O(g)CO(g)+3H2(g) b. 2AgNO3(aq)+Cu(s)Cu(NO3)2(aq)+2Ag(s) c. Zn(s)+2HCl(aq)ZnCl2(aq)+H2(g) d. 2H+(aq)+2CrO42-(aq)Cr2O72-(aq)+H2O(l)The Ostwald process for the commercial production of nitric acid involves the following three steps: 4NH3(g)+5O2(g)4NO(g)+6H2O(g) 2NO(g)+O2(g)2NO2(g) 3NO2(g)+H2O(l)2HNO3,(aq)+NO(g) a. Which reactions in the Ostwald process are oxidationreduction reactions? b. Identify each oxidizing agent and reducing agent.19Q

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