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All Textbook Solutions for Chemistry & Chemical Reactivity
91SCQ92SCQThe reaction cyclopropane propene occurs on a platinum metal surface at 200 C. (The platinum is a catalyst.) The reaction is first-order in cyclopropane. Indicate how the following quantities change (increase, decrease, or no change) as this reaction progresses, assuming constant temperature. (a) [cyclopropane] (b) [propene] (c) [catalyst] (d) the rate constant, k (e) the order of the reaction (f) the half-life of cyclopropane94SCQExamine the reaction coordinate diagram given here. (a) How many steps are in the mechanism for the reaction described by this diagram? (b) Is the reaction overall exothermic or endothermic?Draw a reaction coordinate diagram for an exothermic reaction that occurs in a single step. Identify the activation energy and the net energy change for the reaction on this diagram. Draw a second diagram that represents the same reaction in the presence of a catalyst, assuming a single-step reaction is involved here also. Identify the activation energy of this reaction and the energy change. Is the activation energy in the two drawings different? Does the energy evolved in the two reactions differ?1. Once a chemical equilibrium has been established,
only the forward reaction occurs.
only the reverse reaction occurs.
the forward and reverse reactions occur at an equal rate.
the forward and reverse reactions stop.
Write the equilibrium constant expression for each of the following reactions in terms of concentrations. (a) CO2(g) + C(s) 2 CO(g) (b) [Cu(NH3)4)2+(aq) Cu2+(aq) + 4 NH3(aq) (c) CH3CO2H(aq) + H2O() CH3CO2(aq) + H3O+(aq)Answer the following questions regarding the butane isobutane equilibrium (Kc = 2.50 at 298 K). (a) Is the system at equilibrium when [butane] = 0.00097 M and [isobutane] = 0.00218 M? If not, in which direction will the reaction proceed to achieve equilibrium? (b) Is the system at equilibrium when[butane] = 0.00075 M and [isobutane] = 0.00260M? If not, in which direction will the reaction proceed to achieve equilibrium?1. Which of the following is the correct form of the equilibrium constant expression for the decomposition of SO3 to SO2 and O2?
Kc = [SO2][O2]/[SO3]
Kc = [SO2]2[O2]/[SO3]2
Kc = [SO3]2/[SO2]2[O2]
Kc = [SO2][O2]2
At 2000 K the equilibrium constant for the formation of NO(g) is 4.0 104. N2(g)+O2(g)2NO(g) You have a flask in which, at 2000 K, the concentration of N2 is 0.050 mol/L, that of O2 is 0.025 mol/L, and that of NO is 4.2 104 mol/L. Is the system at equilibrium? (a) Yes, it is at equilibrium. (b) No, it is not at equilibrium, and the reaction proceeds farther to the right. (c) No, it is not at equilibrium, and the reaction proceeds to the left, turning products into reactants.A solution is prepared by dissolving 0.050 mol of diiodocyclohexane, C5H10I2, in the solvent CCl4.The total solution volume is 1.00 L When the reaction C6H10I2 C6H10 + I2 has come to equilibrium at 35 C, the concentration of I2 is 0.035 mol/L. (a) What are the concentrations of C6H10I2 and C6H10 at equilibrium? (b) Calculate Kc, the equilibrium constant.1. You place 0.010 mol of N2O4(g) in a 2.0-L flask at 200°C. After reaching equilibrium, [N2O4] = 0.0042 M. Calculate Kc for the following reaction: N2O4(g) ⇄ 2 NO2.(g)
1640
6.1X104
3.1 x 104
(d) 8.8x106
At some temperature. Kc = 33 for the reaction H2(g) + I2(g) 2 HI(g) Assume the initial concentrations of both H2 and I2 are 6.00 103 mol/L. Find the concentration of each reactant and product at equilibrium.The decomposition of PCl5(g) to form PCl3(g) and Cl2(g) has Kc = 33.3 at a high temperature. If the initial concentration of PCl5 is 0.1000 M, what are the equilibrium concentrations of the reactants and products?1. Graphite and carbon dioxide are kept at constant volume at 1000 K until the reaction
C(graphite) + CO2(g) ⇄ 2 CO(g)
has come to equilibrium. At this temperature, kc = 0.021. The initial concentration of CO2 is 0.012 mol/L. Calculate the equilibrium concentration of CO.
0.012 M
0.011 M
0.0057 M
The conversion of oxygen to ozone has a very small equilibrium constant. 3/2 O2(g) O3(g) K = 2.5 1029 (a) What is the value of K when the equation is written using whole-number coefficients? 3 O2(g) 2 O3(g) (b) What is the value of K for the conversion of ozone to oxygen? 2 O3(g) 3 O2(g)1. The following equilibrium constants are given at 500 K:
What is the value of Kp for the reaction H + Br ⇄ HBr?
Kp = 8.3 × 10−44
Kp = 7.5 × 1066
Kp = 2.7 × 1033
Equilibrium exists between butane and isobutane when [butane] = 0.020 M and [isobutane] = 0.050 M. An additional 0.0200 mol/L of isobutane is added to the mixture. What are the concentrations of butane and isobutane after equilibrium has again been attained?Anhydrous ammonia is used directly as a fertilizer, but much of it is also converted to other fertilizers such as ammonium nitrate and urea. a. Write a balanced equation for the conversion of ammonia to ammonium nitrate. b. Urea is formed in the reaction of ammonia and CO2. 2 NH3(g) + CO2(g) (NH2)2CO(s) + H2O(g) Would high pressure favor urea production? Would high temperature? fH for solid urea = 333.1 kJ/mol-rxn). Explain your answers.2QFreezing point depression is one means of determining the molar mass of a compound. The freezing point depression constant of benzene is 5.12 C/m. a. When a 0.503 g sample of the white crystalline dimer is dissolved in 10.0 g benzene, the freezing point of benzene is decreased by 0542 C. Verify that the molar mass of the dimer is 475 g/mol when determined by freezing point depression. Assume no dissociation of the dimer occurs. b. The correct molar mass of the dimer is 487 g/mol. Explain why the dissociation equilibrium causes the freezing point depression calculation to yield a lower molar mass for the dimer.2QA 0.64 g sample of the white crystalline dimer (4) is dissolved in 25.0 mL of benzene at 20 C. Use the equilibrium constant to calculate the concentrations of monomer (2) and dimer (4) in this solution.Predict whether the dissociation of the dimer to the monomer is exothermic or endothermic, based on the tact that at higher temperatures the yellow color of the solution intensifies.5QThe formation of ammonia from its elements is an important industrial process. 3 H2(g) + N2(g) 2 NH3(g) 1. Does the reaction shift to the right or to the left, or does it remain unchanged, when extra H2 is added? (a) shift left (b) shift right (c)unchanged2RC3RCWrite equilibrium constant expressions for the following reactions. For gases, use either pressures or concentrations. (a) 2 H2O2(g) 2 H2O(g) + O2(g) (b) CO(g) + O2g CO2(g) (c) C(s) + CO2(g) 2 CO(g) (d) NiO(s) + CO(g) Ni(s) + CO2(g)Write equilibrium constant expressions for the following reactions. For gases, use either pressures or concentrations. (a) 3 O2(g) 2 O3(g) (b) Fe(s) + 5 CO(g) Fe(CO)5(g) (c) (NH4)2CO3(s) 2 NH3(g) + CO2(g) + H2O(g) (d) Ag2SO4(s) 2 Ag+(aq) + SO42(aq)Kc = 5.6 1012 at 500 K for the dissociation of iodine molecules to iodine atoms. I2(g) 2 I(g) A mixture has [I2] = 0.020 mol/Land [I] = 2.0 108 mol/L. Is the reaction at equilibrium (at 500 K)? If not, which way must the reaction proceed to reach equilibrium?The reaction 2 NO2(g) N2O4(g) has an equilibrium constant, Kc, of 170 at 25 C. If 2.0 103 mol of NO2 is present in a 10.-L. Flask along with 1.5 103 mol of N2O4, is the system at equilibrium? If it is not at equilibrium, does the concentration of NO2 increase or decrease as the system proceeds to equilibrium?A mixture of SO2, O2, and SO3 at 1000 K contains the gases at the following concentrations: [SO2] = 5.0 103 mol/L, [O2] = 1.9 103 mol/L, and [SO3] = 6.9 103 mol/L. Is the reaction at equilibrium? If not, which way will the reaction proceed to reach equilibrium? 2 SO2(g) + O2(g) 2 SO3(g) Kc = 279The equilibrium constant Kc, for the reaction 2 NOCI(g) 2 NO(g) + Cl2(g) is 3.9 103 at 300 C. A mixture contains the gases at the following concentrations: [NOCl] = 5.0 103 mol/L, [NO] = 2.5 103 mol/L, and [Cl2] = 2.0 103 mol/L. Is the reaction at equilibrium at 300 C? If not, in which direction does the reaction proceed to come to equilibrium?The reaction PCl5(g) PCl3(g) + Cl2(g) was examined at 250 C. At equilibrium, [PCl5] = 4.2 105 mol/L, [PCl3] = 1.3 102 mol/L, and [Cl2] = 3.9 103 mol/L. Calculate Kc, for the reaction.An equilibrium mixture of SO2, O2, and SO3 at a high temperature contains the gases at the following concentrations: |SO2| = 3.77 103 mol/L, [O2] = 4.30 103 mol/L, and [SO3] = 4.13 103 mol/L. Calculate the equilibrium constant, Kc, for the reaction. 2 SO2(g) + O2(g) 2 SO3(g)The reaction C(s) + CO2(g) 2 CO(g) occurs at high temperatures. At 700 C, a 200.0-L tank contains 1.0 mol of CO, 0.20 mol of CO2, and 0.40 mol of C at equilibrium. (a) Calculate Kc for the reaction at 700 C. (b) Calculate Kc for the reaction, also at 700 C, if the amounts at equilibrium in the 200.0-L tank are 1.0 mol of CO, 0.20 mol of CO2, and 0.80 mol of C. (c) Compare the results of (a) and (b). Does the quantity of carbon affect the value of Kc? Explain.Hydrogen and carbon dioxide react at a high temperature to give water and carbon monoxide. H2(g) + CO2(g) H2O(g) + CO(g) (a) Laboratory measurements at 986 C show that there are 0.11 mol each of CO and H2O vapor and 0.087 mol each of H2 and CO2 at equilibrium in a 50.0-L container. Calculate the equilibrium constant for the reaction at 986 C. (b) Suppose 0.010 mol each of H2 and CO2 are placed in a 200.0-L container. When equilibrium is achieved at 986 C, what amounts of CO(g) and H2O(g), in moles, would be present? [Use the value of Kc from part (a).]A mixture of CO and Cl2 is placed in a reaction flask: [CO] = 0.0102 mol/L and [Cl2] = 0.00609 mol/L. When the reaction CO(g) + Cl2(g) COCl2(g) has come to equilibrium at 600 K, [Cl2] = 0.00301 mol/L. (a) Calculate the concentrations of CO and COCl2 at equilibrium. (b) Calculate KC.You place 0.0300 mol of pure SO3 in an 8.00-L flask at 1150 K. At equilibrium, 0.0058 mol of O2 has been formed. Calculate Kc for the reaction at 1150 K. 2 SO3(g) 2 SO2(g) + O2(g)The value of Kc for the interconversion of butane and isobutane is 2.5 at 25 C. If you place 0.017 mol of butane in a 0.50-L flask at 25 C and allow equilibrium to be established, what will be the equilibrium concentrations of the two forms of butane?Cyclohexane, C6H12, a hydrocarbon, can isomerize or change into methylcyclopentane, a compound of the same formula (C5H9CH3) but with a different molecular structure. sssss The equilibrium constant has been estimated to be 0.12 at 25 C. If you had originally placed 0.045 mol of cyclohexane in a 2.8-L flask, what would be the concentrations of cyclohexane and methylcyclopentane when equilibrium is established?The equilibrium constant for the dissociation of iodine molecules to iodine atoms I2(g) 2 I(g) is 3.76 103 at 1000 K. Suppose 0.105 mol of I2 is placed in a 12.3-L flask at 1000 K. What are the concentrations of I2 and I when the system comes to equilibrium?The equilibrium constant, Kc, for the reaction N2O4(g) 2 NO2(g) at 25 C is 5.9 103. Suppose 15.6 g of N2O4 placed in a 5.000-L flask at 25 C. Calculate the following; (a) the amount of NO2 (mol) present at equilibrium; (b) the percentage of the original N2O4 that is dissociated.Carbonyl bromide decomposes to carbon monoxide and bromine. COBr2(g) CO(g) + Br2(g) Kc is 0.190 at 73 C. If you place 0.0500 mol of COBr2 in a 2.00-L flask and heat it to 73 C, what are the equilibrium concentrations of COBr2, CO, and Br2? What percentage of the original COBr2 decomposed at this temperature?Iodine dissolves in water, but its solubility in a nonpolar solvent such as CCl4 is greater. Extracting iodine (I2) from water with the nonpolar solvent CCl4. I2 is more soluble in CCl4 and, after shaking a mixture of water and CCl4, the I2 has accumulated in the more dense CCl4 layer. The equilibrium constant is 85.0 for the process I2(aq) I2(CCl4) You place 0.0340 g of I2 in 100.0 mL of water. After shaking it with 10.0 mL of CCl4, how much I2 remains in the water layer?Which of the following correctly relates the equilibrium constants for the two reactions shown? A+B2CK12A+2B4CK2 (a) K2 = 2K1 (b) K2 = K12 (c) K2 = 1/K1 (d) K2 = l/K12Which of the following correctly relates the equilibrium constants for the two reactions shown? A+B2CK1C12A+12BK2 (a) K2 = 1/(K1)1/2 (b) K2 = 1/K1 (c) K2 = K12 (d) K2 = K11/2Consider the following equilibria involving SO2(g) and their corresponding equilibrium constants. SO2(g)+O2(g)SO3(g)K12SO3(g)2SO2(g)+O2(g)K2 Which of the following expressions relates K1 to K2? (a) K2 = K12 (b) K22 = K1 (c) K2 = K1 (d) K2 = 1/K1 (e) K2 = 1/K12The equilibrium constant K for the reaction CO2(g) CO(g) + O2(g) is 6.66 1012 at 1000 K. Calculate K for the reaction 2 CO(g) + O2(g) 2 CO2(g)Calculate K for the reaction SnO2(s) + 2 CO(g) Sn(s) + 2 CO2(g) given the following information: SnO2(s)+2H2(g)Sn(s)+2H2O(g)K=8.12H2(g)+CO2(g)H2O(g)+CO(g)K=0.771Calculate K for the reaction Fe(s) + H2O(g) FeO(s) + H2(g) given the following information: H2O(g)+CO(g)H2(g)+CO2(g)K=1.6FeO(s)+CO(g)Fe(s)+CO2(g)K=0.67Relationship of Kc and Kp: (a) Kp for the following reaction is 0.16 at 25 C. What is the value of Kc? 2 NOBr(g) 2 NO(g) + Br2(g) (b) The equilibrium constant, Kc, for the following reaction is 1.05 at 350 K. What is the value of Kp? 2 CH2Cl2(g) CH4(g) + CCl4(g)Relationship of Kc and Kp: (a) The equilibrium constant, Kc, for the following reaction at 25 C is 170. What is the value of Kp? N2O4(g) 2 NO2(g) (b) Kc for the decomposition of ammonium hydrogen sulfide is 1.8 104 at 25 C. What is the value of Kp? NH4HS(s) NH3(g) + H2S(g)Dinitrogen trioxide decomposes to NO and NO2, in an endothermic process (rH = 40.5 kJ/mol-rxn). N2O3(g) NO(g) + NO2(g) Predict the effect of the following changes on the position of the equilibrium; that is, state which way the equilibrium will shift (left, right, or no change) when each of the following changes is made. (a) adding more N2O3(g) (b) adding more NO2(g) (c) increasing the volume of the reaction flask (d) lowering the temperatureKp for the following reaction is 0.16 at 25 C: 2 NOBr(g) 2 NO(g) + Br2(g) The enthalpy change for the reaction at standard conditions is + 16.3 kJ/mol-rxn. Predict the effect of the following changes on the position of the equilibrium; that is, state which way the equilibrium will shift (left, right, or no change) when each of the following changes is made. (a) adding more Br2(g) (b) removing some NOBr(g) (c) decreasing the temperature (d) increasing the container volumeConsider the isomerization of butane with an equilibrium constant of K = 2.5. (See Study Question 13.) The system is originally at equilibrium with [butane] = 1.0 M and [isobutane] = 2.5 M. (a) If 0.50 mol/L of isobutane is suddenly added and the system shifts to a new equilibrium position, what is the equilibrium concentration of each gas? (b) If 0.50 mol/L of butane is added to the original equilibrium mixture and the system shifts to a new equilibrium position, what is the equilibrium concentration of each gas?The decomposition of NH4HS NH4HS(s) NH3(g) + H2S(g) is an endothermic process. Using Le Chateliers principle, explain how increasing the temperature would affect the equilibrium. If more NH4HS is added to a flask in which this equilibrium exists, how is the equilibrium affected? What if some additional NH3 is placed in the flask? What will happen to the pressure of NH3 if some H2S is removed from the flask?Suppose 0.086 mol of Br2 is placed in a 1.26-L flask and heated to 1756 K, a temperature at which the halogen dissociates to atoms. Br2(g) 2 Br(g) If Br2 is 3.7% dissociated at this temperature, calculate Kc.The equilibrium constant for the reaction N2(g) + O2(g) 2 NO(g) is 1.7 103 at 2300 K. (a) What is K for the reaction when written as follows? N2(g) + O2(g) NO(g) (b) What is K for the following reaction? 2 NO(g) N2(g) + O2(g)Kp for the formation of phosgene, COCl2, is 6.5 1011 at 25 C. CO(g) + Cl2(g) COCl2(g) What is the value of Kp for the dissociation of phosgene? COCl2(g) CO(g) + Cl2(g)The equilibrium constant, Kc, for the following reaction is 1.05 at 350 K. 2 CH2Cl2(g) CH4(g) + CCl4(g) If an equilibrium mixture of the three gases at 350 K contains 0.0206 M CH2Cl2(g) and 0.0163 M CH4, what is the equilibrium concentration of CCl4?Carbon tetrachloride can be produced by the following reaction: CS2(g) + 3 Cl2(g) S2Cl2(g) + CCl4(g) Suppose 0.12 mol of CS2 and 0.36 mol of Cl2 are placed in a 10.0-L flask. After equilibrium has been achieved, the mixture contains 0.090 mol CCl4. Calculate Kc.Equal numbers of moles of H2 gas and I2 vapor are mixed in a flask and heated to 700 C. The initial concentration of each gas is 0.0088 mol/L, and 78.6% of the I2 is consumed when equilibrium is achieved according to the equation H2(g) + I2(g) 2 HI(g) Calculate Kc for this reaction.The equilibrium constant for the butane isobutane isomerization reaction is 2.5 at 25 C. If 1.75 mol of butane and 1.25 mol of isobutane are mixed, is the system at equilibrium? If not, when it proceeds to equilibrium, which reagent increases in concentration? Calculate the concentrations of the two compounds when the system reaches equilibrium.At 2300 K the equilibrium constant for the formation of NO(g) is 1.7 103. N2(g) + O2(g) 2 NO(g) (a) Analysis shows that the concentrations of N2 and O2 are both 0.25 M, and that of NO is 0.0042 M under certain conditions. Is the system at equilibrium? (b) If the system is not at equilibrium, in which direction does the reaction proceed? (c) When the system is at equilibrium, what are the equilibrium concentrations?Which of the following correctly relates the two equilibrium constants for the two reactions shown? NOCl(g) NO(g) + Cl2(g)K1 2 NO(g) + Cl2(g) 2 NOCI(g)K2 (a) K2 = K12 (b) K2 = 1/(K1)1/2 (c) K2 = 1/K12 (d) K2 = 2K1Consider the following equilibrium: COBr2(g) CO(g) + Br2(g)Kc = 0.190 at 73 C (a) A 0.50 mol sample of COBr2 is transferred to a 9.50-L flask and heated until equilibrium is attained. Calculate the equilibrium concentrations of each species. (b) The volume of the container is decreased to 4.5 L and the system allowed to return to equilibrium. Calculate the new equilibrium concentrations. (Hint: The calculation will be easier if you view this as a new problem with 0.5 mol of COBr2 transferred to a 4.5-L flask.) (c) What is the effect of decreasing the container volume from 9.50 L to 4.50 L?Heating a metal carbonate leads to decomposition. BaCO3(s) BaO(s) + CO2(g) Predict the effect on the equilibrium of each change listed below. Answer by choosing (i) no change, (ii) shifts left or (iii) shifts right. (a) add BaCO3 (b) add CO2 (c) add BaO (d) raise the temperature (e) increase the volume of the flask containing the reactionPhosphorus pentachloride decomposes at elevated temperatures. PCl5(g) PCl3(g) + Cl2(g) An equilibrium mixture at some temperature consists of 3.120 g of PCl5, 3.845 g of PCl3, and 1.787 g of Cl2 in a 10.0-L flask. If you add 1.418 g of Cl2, how will the equilibrium be affected? What will the concentrations of PCl5, PCl3, and Cl2 be when equilibrium is reestablished?Ammonium hydrogen sulfide decomposes on heating. NH4HS(s) NH3(g) + H2S(g) If Kp for this reaction is 0.11 at 25 C (when the partial pressures are measured in atmospheres), what is the total pressure in the flask at equilibrium?Ammonium iodide dissociates reversibly to ammonia and hydrogen iodide if the salt is heated to a sufficiently high temperature. NH4I(s) NH3(g) + HI(g) Some ammonium iodide is placed in a flask, which is then heated to 400 C. If the total pressure in the flask when equilibrium has been achieved is 705 mm Hg, what is the value of Kp (when partial pressures are in atmospheres)?When solid ammonium carbamate sublimes, it dissociates completely into ammonia and carbon dioxide according to the following equation: (NH4)(H2NCO2)(s) 2 NH3(g) + CO2(g) At 25 C, experiment shows that the total pressure of the gases in equilibrium with the solid is 0.116 atm. What is the equilibrium constant, Kp?In the gas phase, acetic acid exists as an equilibrium of monomer and dimer molecules. (The dimer consists of two molecules linked through hydrogen bonds.) The equilibrium constant, Kc, at 25 C for the monomer-dimer equilibrium 2 CH3CO2H (CH3CO2H)2 has been determined to be 3.2 104. Assume that acetic acid is present initially at a concentration of 5.4 104 mol/L at 25 C and that no dimer is present initially. (a) What percentage of the acetic acid is converted to dimer? (b) As the temperature increases, in which direction does the equilibrium shift? (Recall that hydrogen-bond formation is an exothermic process.)Assume 3.60 mol of ammonia is placed in a 2.00-L vessel and allowed to decompose to the elements at 723 K. 2 NH3(g) N2(g) + 3 H2(g) If the experimental value of Kc is 6.3 for this reaction at the temperature in the reactor, calculate the equilibrium concentration of each reagent. What is the total pressure in the flask?The total pressure for a mixture of N2O4 and NO2 is 0.15 atm. If Kp = 7.1 (at 25 C), calculate the partial pressure of each gas in the mixture. 2 NO2(g) N2O4(g)Kc for the decomposition of ammonium hydrogen sulfide is 1.8 104 at 25 C. NH4HS(s) NH3(g) + H2S(g) (a) When the pure salt decomposes in a flask, what are the equilibrium concentrations of NH3 and H2S? (b) If NH4HS is placed in a flask already containing 0.020 mol/L of NH3 and then the system is allowed to come to equilibrium, what are the equilibrium concentrations of NH3 and H2S?52GQA 15-L flask at 300 K contains 6.44 g of a mixture of NO2 and N2O4 in equilibrium. What is the total pressure in the flask? (Kp for 2 NO2 (g) N2O4(g) is 7.1.)Lanthanum oxalate decomposes when heated to lanthanum(III) oxide, CO, and CO2. La2(C2O4)3(s) La2CO3(s) + 3 CO(g) + 3 CO2(g) (a) If, at equilibrium, the total pressure in a 10.0-L flask is 0.200 atm, what is the value of Kp? (b) Suppose 0.100 mol of La2(C2O4)3 was originally placed in the 10.0-L flask. What quantity of La2(C2O4)3 remains unreacted at equilibrium at 373 K?The reaction of hydrogen and iodine to give hydrogen iodide has an equilibrium constant, Kc, of 56 at 435 C. (a) What is the value of Kp? (b) Suppose you mix 0.045 mol of H2 and 0.045 mol of I2 in a 10.0-L flask at 425 C. What is the total pressure of the mixture before and after equilibrium is achieved? (c) What is the partial pressure of each gas at equilibrium?Sulfuryl chloride, SO2Cl2 is used as a reagent in the synthesis of organic compounds. When heated to a sufficiently high temperature, it decomposes to SO2 and Cl2. SO2Cl2(g) SO2(g) + Cl2(g)Kc = 0.045 at 375 C (a) A 10.0-L flask containing 6.70 g of SO2Cl2 is heated to 375 C. What is the concentration of each of the compounds in the system when equilibrium is achieved? What fraction of SO2Cl2 has dissociated? (b) What are the concentrations of SO2Cl2, SO2, and Cl2 at equilibrium in the 10.0-L flask at 375 C if you begin with a mixture of SO2Cl2 (6.70 g) and Cl2 (0.10 atm)? What fraction of SO2Cl2 has dissociated? (c) Compare the fractions of SO2Cl2 in parts (a) and (b). Do they agree with your expectations based on Le Chateliers principle?Hemoglobin (Hb) can form a complex with both O2 and CO. For the reaction HbO2(aq) + CO(g) HbCO(aq) + O2(g) at body temperature, K is about 200. If the ratio [HbCO]/[HbO2) comes close to 1, death is probable. What partial pressure of CO in the air is likely to be fatal? Assume the partial pressure of O2 is 0.20 atm.Limestone decomposes at high temperatures. CaCO3(s) CaO(s) + CO2(g) At 1000 C, Kp = 3.87. If pure CaCO3 is placed in a 5.00-L flask and heated to 1000 C, what quantity of CaCO3 must decompose to achieve the equilibrium pressure of CO2?At 1800 K, oxygen dissociates very slightly into its atoms. O2(g) 2 O(g)KP= 1.2 1010 If you place 0.050 mol of O2 in a 10.-L vessel and heat it to 1800 K, how many O atoms are present in the flask?Nitrosyl bromide, NOBr, dissociates readily at room temperature. NOBr(g) NO(g) + Br2(g) Some NOBr is placed in a flask at 25 C and allowed to dissociate. The total pressure at equilibrium is 190 mm Hg and the compound is found to be 34% dissociated. What is the value of Kp?A Boric acid and glycerin form a complex B(OH)3(aq) + glycerin(aq) B(OH)3 glycerin(aq) with an equilibrium constant of 0.90. If the concentration of boric acid is 0.10 M, how much glycerin should be added, per liter, so that 60.% of the boric acid is in the form of the complex?The dissociation of calcium carbonate has an equilibrium constant of Kp = 1.16 at 800 C. CaCO3(s) CaO(s) + CO2(g) (a) What is Kc for the reaction? (b) If you place 22.5 g of CaCO3 in a 9.56-L container at 800 C, what is the pressure of CO2 in the container? (c) What percentage of the original 22.5-g sample of CaCO3 remains undecomposed at equilibrium?A sample of N2O4 gas with a pressure of 1.00 atm is placed in a flask. When equilibrium is achieved, 20.0% of the N2O4 has been convened to NO2 gas. (a) Calculate Kp. If the original pressure of N2O4 is 0.10 atm, what is the percent dissociation of the gas? Is the result in agreement with Le Chateliers principle?64GQThe photograph below shows what occurs when a solution of potassium chromate is treated with a few drops of concentrated hydrochloric acid. Some of the bright yellow chromate ion is converted to the orange dichromate ion. 2 CrO42(aq) + 2 H3O+(aq) CrO72(aq) + 3 H2O() (a) Explain this experimental observation in terms of Le Chateliers principle. (b) What would you observe if you treated the orange solution with sodium hydroxide? Explain your observation.The photographs below (a) show what occurs when a solution of iron(III) nitrate is treated with a few drops of aqueous potassium thiocyanate. The nearly colorless iron(III) ion is converted to a red [Fe(H2O)5SCN)2+ ion. (This is a classic test for the presence of iron(III) ions in solution.) [Fe(H2O)6]3+(aq) + SCN(aq) [Fe(H2O)5SCN]2+(aq) + H2O() (a) As more KSCN is added to the solution, the color becomes even more red. Explain this observation. (b) Silver ions form a white precipitate with SCN ions. What would you observe on adding a few drops of aqueous silver nitrate to a red solution of [Fe(H2O)5 SCN]+ ions? Explain your observation.Decide whether each of the following statements is true or false. If false, change the wording to make it true. (a) The magnitude of the equilibrium constant is always independent of temperature. (b) When two chemical equations are added to give a net equation, the equilibrium constant for the net equation is the product of the equilibrium constants of the summed equations. (c) The equilibrium constant for a reaction has the same value as K for the reverse reaction. (d) Only the concentration of CO2 appears in the equilibrium constant expression for the reaction CaCO3(s) CaO(s) + CO2(g). (e) For the reaction CaCO3(s) CaO(s) + CO2(g), the value of K is numerically the same, whether the amount of CO2 is expressed as moles/liter or as gas pressure.Neither PbCl2 nor PbF2 is appreciably soluble in water. If solid PbCl2 and solid PbF2 are placed in equal amounts of water in separate beakers, in which beaker is the concentration of Pb2+ greater? Equilibrium constants for these solids dissolving in water are as follows: PbCl2(s) Pb2+(aq) + 2 Cl(aq)Kc = 1.7 105 PbF2(s) Pb2+(aq) + 2 F(aq)Kc = 3.7 108Characterize each of the following as product- or reactant-favored at equilibrium. (a) CO(g) + O2(g) CO2(g)Kp = 1.2 1045 (b) H2O(g) H2(g) + O2(g)Kp = 9.1 1041 (c) CO(g) + Cl2(g) COCl2(g)Kp = 9.1 1011The size of a flask containing colorless N2O4(g) and brown NO2(g) at equilibrium is rapidly reduced to half the original volume. N2O4(g) 2 NO2(g) (a) What color change (if any) is observed immediately upon halving the flask size? (b) What color change (if any) is observed during the process in which equilibrium is reestablished in the flask?Describe an experiment that would allow you to prove that the system 3 H2(g) + N2(g) 2 NH3(g) is a dynamic equilibrium. (Hint: Consider using a stable isotope such as 15N or 2H.)Suppose a tank initially contains H2S at a pressure of 10.00 atm and a temperature of 800 K. When the reaction has come to equilibrium, the partial pressure of S2 vapor is 0.020 atm. Calculate Kp. 2 H2S(g) 2 H2(g) + S2(g)Pure PCl5 gas is placed in a 2.00-L flask. After heating to 250 C the pressure of PCl5 is initially 2.000 atm. However, the gas slowly but only partially decomposes to gaseous PCl3 and Cl2. When equilibrium is reached, the partial pressure of Cl2 0.814 atm. Calculate Kp for the decomposition.1. H3PO4 phosphoric acid, can donate two protons to water to form the hydrogen phosphate ion, HPO42−. Is the ion an acid or a base, or is it amphiprotic?
acid
base
amphiprotic
2. The cyanide ion, CN−, accepts a proton from water to form HCN. Is CN− a Bronsted acid or base or is it amphiprotic?
acid
base
amphiprotic
3. In the following reaction, identify the acid on the left and its conjugate base on the right. HNO3(aq) + NH3(aq) ⇄ NH4+(aq) + NO3−(aq)
acid = NH3 and conjugate base = NH4+
acid = HNO3 and conjugate base NO3−
Similarly, identify the base on the left and its conjugate acid on the right.
base = NH3 and conjugate acid = NH4+
base = HNO* and conjugate acid = NO3−
4RCWhat are the hydronium ion and hydroxide ion concentrations in 4.0 103 M HCI(aq) at 25 C? (Recall that because HCl is a strong acid, it is 100% ionized in water.)What is the pH of a 0.0012 M NaOH solution at 25C? (a) 2.92 (b) 11.08 (c) 8.67The pH of a diet soda is 432 at 25C. What is the hydronium ion concentration in the soda? (a) 4.8 105 M (b) 2.11010 M (c) 2.1 104 MIf the pH of a solution containing the strong base Sr(OH)2 is 10.46 at 25C, what is the concentration of Sr(OH)2? (a) 3.5 1011 M (b) 2.9 104 M (c) 6.9 104 M (d) 1.4 104 M1RCWhich acid has the strongest conjugate base? (a) HNO2 (b) C6H5CO2H (c) HCN (d) HCl3RC4RC5RCFor each of the following salts in water, predict whether the pH will be greater than, less than, or equal to 7. (a) KBr (b) NH3NO3 (c) AlCl3 (d) Na2HPO41RC2RC(a) Which is the stronger Bronsted acid, HCO3 or NH4+? Which has the stronger conjugate base? (b) Is a reaction between HCO3- ions and NH3 product- or reactant-favored at equilibrium? HCO3(aq) + NH3(aq) CO32(aq) + NH4+(aq) (c) You mix solutions of sodium hydrogen phosphate and ammonia. The net ionic equation for a possible reaction is HPO42(aq) + NH3(aq) PO43(aq) + NH4+(aq) Does the equilibrium lie to the left or to the right for this reaction?1RC2. In the following reaction, does the equilibrium lie predominantly to the left or to the right?
HS−(aq) + H3PO4(aq) ⇄ H2S(aq) + HzPO4−(aq)
left
right
Equal amounts (moles) of HCl(aq) and NaCN(aq) are mixed. The resulting solution is (a) acidic (b) basic (c) neutral2. Equal amounts (moles) of acetic acid(aq) and sodium sulfite, Na2SO3(aq), are mixed. The resulting solution is
acidic
basic
neutral
3RCA solution prepared from 0.055 mol of butanoic acid and sufficient water to give 1.0 L of solution has a pH of 2.72. Determine Ka for butanoic acid. The acid ionizes according to the balanced equation CH3CH2CH2CO2H(aq) + H2O(l) H3O+(aq) + CH3CH2CH2CO2(aq)What are the equilibrium concentrations of acetic acid, the acetate ion, and H3O+ for a 0.10 M solution of acetic acid (K2 = 1.8 105)? What is the pH of the solution?What are the equilibrium concentrations of HF, F ion, and H3O+ ion in a 0.00150 M solution of HF? What is the pH of the solution?The weak base, CIO (hypochlorite ion), is used in the form of NaCIO as a disinfectant in swimming pools and water treatment plants. What are the concentrations of HCIO and OH and the pH of a 0.015 M solution of NaCIO?Calculate the pH after mixing 15 mL of 0.12 M acetic acid with 15 ml of 0.12 M NaOH. What are the major species in solution at equilibrium (besides water), and what are their concentrations?1. What is [H3O+] in a 0.10 M solution of HCN at 25°C? (K, for HCN = 4.0 × 10−10)
1.6 × 10−9 M
6.3 × 10−6 M
2.0 × 10−5 M
4.0 × 10−11 M
2. A 0.040 M solution of an acid, HA, has a pH of 3.02 at 25°C. What is Ka for this acid?
23 × 10−5
5.7 × 10−4
2.4 × 10−2
4.3 × 10−10
What are the pH and ion concentrations in a solution of 0.10 M sodium formate, NaCHO2? Kb for the formate ion, HCO2 is 5.6 1011. pH [Na+] [CHO2] [OH] (a) 5.63 0.10 0.10 2.4 10-6 (b) 837 0.10 0.10 2.4 10 6 (c) 822 0.050 0.050 17 10- (d) 5.63 0.10 0.10 42 104RCWhat is the pH of a 0.10 M solution of oxalic acid, H2C2C4? What are the concentrations of H3O+, HC2O4, and the oxalate ion, C2O42? (See Appendix H for Ka values.)Hydrazine (N2H4) is like CO32 in that it is a polyprotic base (Kb1 = 85 107 and Kb2 = 8.9 1016). The two conjugate acids are N2H5+ and N2H62+. What is the expected pH of a 0.025 M solution of N2H4? (a) 3.83 (b) 8.32 (c) 10.16Which of the following is the stronger acid? (a) H2SeO4 (b) H2SeO32RC3RC1. Which of the following can act as a Lewis acid? (Hint : In each case, draw the Lewis electron dot structure of the molecule or ion. Are there lone pairs of electrons on the central atom? If so, it can be a Lewis base. Does the central atom lack an electron pair? If so, it can behave as a Lewis acid.)
PH3
BCl3
H2S
HS−
2. The molecule whose structure is illustrated here is amphetamine, a stimulant Which description best fits this molecule? (Note: There may be more than one answer.)
Brønsted acid
Lewis acid
Brønsted base
Lewis base
1Q2QThe pKa, of the conjugate acid of atropine is 4.35. How does this compare with the pKa values for the conjugate acids of ammonia, methylamine, and aniline?Convert the pK values to K values for the ionization of HCl, HClO4, and H2SO4 in glacial acetic acid. Rank these acids in order from strongest to weakest.Other solvents also undergo autoionization. (a) Write a chemical equation for the autoionization of glacial acetic acid. (b) The equilibrium constant for the autoionization of glacial acetic acid is 32 1015 at 25C. Determine the concentration of [CH3CO2H2]+ in acetic acid at 25C.3Q4QTo measure the relative strengths of bases stronger than OH, it is necessary to choose a solvent that is a weaker acid than water. One such solvent is liquid ammonia. (a) Write a chemical equation for the autoionization of ammonia. (b) What is the strongest acid and base that can exist in liquid ammonia? (c) Will a solution of HCI in liquid ammonia be a strong electrical conductor, a weak conductor, or a nonconductor? (d) Oxide ion (O2) is a stronger base than the amide ion (NH2). Write an equation for the reaction of O2 with NH3 in liquid ammonia. Will the equilibrium favor products or reactants?Write the formula and the give the name of the conjugate base of each of the following acids. a) HCN b) HSO4 c) HFWrite the formula and give the name of the conjugate base of each of the following acids. a) NH3 b) HCO3 c) BrWhat are the products of each of the following acid-base reactions? Indicate the acid and its conjugate base and the base and its conjugate acid. a) HNO3+H2O b) HSO4+H2O c) sH3O++FWhat are the products of each of the following acid-base reactions? Indicate the acid and its conjugate base and the base and its conjugate acid. (a) HCIO4 + H2O (b) NH4 ++ H2O (c) HCO3 + OHWrite balanced equations showing how the hydrogen oxalate ion, HC2O4, can be both a Bronsted acid and a Bronsted base.Write a balanced equation showing how the HPO42 ion of sodium hydrogen phosphate Na2HPO4 can be a both conjugated acid and conjugated base.In each of the following acid-base reactions, identify the Brnsted acid and base on the left and their conjugate partners on the right. (a) HCO2H(aq) + H2O() HCO2(aq) + H3O+(aq) (b) NH3(aq) + H2S(aq) NH4+(aq) + HS(aq) (c) HSO4(aq) + OH(aq) SO42(aq) + H2O+()In each of the following acid-base reactions, identify the Brnsted acid and base on the left and their conjugate partners on the right. (a) C2H5N(aq) + CH3CO2H(aq) C5H5NH+(aq) + CH3CO2(aq) (b) N2H4(aq) + HSO4(aq) N2H5+(aq) + SO42(aq) (c) [Al(H2O)6]3+ (aq) + OH(aq) [Al(H2O)5OH]2+ (aq) + H2O+()An aqueous solution has a pH of 3.75. What is the hydronium ion concentration of the solution? Is it acidic or basic?A saturated solution of milk of magnesia. Mg(OH)2, has a pH of 10.52. What is the hydronium ion concentration of the solution? What is the hydroxide ion concentration? Is the solution acidic or basic?What is the pH of a 0.0075 M solution of HCl? What is the hydroxide ion concentration of the solution?What is the pH of a 1.2 104 M solution of KOH? What is the hydronium ion concentration of the solution?What is the pH of a 0.0015 M solution of Ba(OH)2?The pH of a solution of Ba(OH)2 is 10.66 at 25 . What is the hydroxide ion concentration in the solution? If the solution volume is 125 mL, what mass of Ba(OH)2 must have been dissolved?Several acids are listed here with their respective equilibrium constants: C6H5OH(aq) + H2O() H3O+(aq) + C6H5O(aq) Ka = 1.3 1010 HCO2H(aq) + H2O() H3O+(aq) + HCO2(aq) Ka = 1.8 104 HC2O4(aq) H2O() H3O+(aq) + C2O42(aq) Ka = 6.4 105 (a) Which is the strongest acid? Which is the weakest acid? (b) Which acid has the weakest conjugate base? (c) Which acid has the strongest conjugate base?Several acids are listed here with their respective equilibrium constants: HF(aq) + H2O() H3O+(aq) + F(aq) Ka = 7.2 104 HPO42(aq) + H2O() H3O+(aq) + PO43(aq) Ka = 3.6 1013 CH3CO2(H) + H2O() H3O+(aq) + CH3CO2(aq) Ka = 1.8 105 (a) Which is the strongest acid? Which is the weakest acid? (b) What is the conjugate base of the acid I IF? (c) Which acid has the weakest conjugate base? (d) Which acid has the strongest conjugate base?Which of the following ions or compounds has the strongest conjugate base? Briefly explain your choice. (a) HSO4 (b) CH3CO2H (c) HOClWhich of the following compounds or ions has the weakest conjugate base? Briefly explain your choice. a) HCN b) HClO c) NH4+Which of the following compounds or ions has the weakest conjugate acid? Briefly explain your choice. (a) HCO3 (b) F (c) NO2Which of the following compounds or ion has the strongest conjugate acid? Briefly explain your choice. (a) CN (b) NH3 (c) SO42Dissolving K2CO3 in water gives a basic solution. Rite a balanced equation showing how this can occur.Dissolving ammonium bromide in water gives an acidic solution. Write a balanced equation showing this can occur.If each of the salts listed here were dissolved in water to give 0.10M solution, which solution would have the highest pH? Which would have the lowest pH? (a) Na2S (b) Na3PO4 (c) NaH2PO4 (d) NaF (e) NaCH3CO2 (f) AlCl3Which of the following common food additives gives a basic solution when dissolved in water? (a) NaNO3 (used as a meat preservative) (b) NaC6H5CO2(Sodium benzoate, used as a soft drink preservative) (c) NaH2PO4(used as a emulsifier in the manufacture of pasteurized cheese)25PS26PS27PSAn organic acid has pKa = 8.95. What is its Ka value? Where does the acid fit in Table 16.2? TABLE 16.2 Ionization Constants for Some Acids and Their Conjugate Bases at 25 C29PSWhich is the stronger of the following two acids? (a) acetic acid, CH3CO2H, Ka = 1.8 105 (b) chloroacetic acid, ClCH2CO2H, pKa = 2.85Chloroacetic acid (ClCH2CO2H) has Ka = 1.41 103. What is the value of Kb for the chloroacetate ion (ClCH2CO2)?A weak base has Kb = 1.5 109. What is the value of Ka for the conjugate acid?The trimethylammonium ion, (CH3)3NH+, is the conjugate acid of the weak base trimethylamine, (CH3)3N. A chemical handbook gives 9.80 as the pKa value for (CH3)3NH+. What is the value of for(CH3)3N?The chromium(III) ion in water, [Cr(H2O)6]3+. Is a weak acid with pKa = 3.95. What is the value of Kb for its conjugate base, [Cr(H2O)5OH]2+?Acetic acid and sodium hydrogen carbonate, NaHCO3, are mixed in water. Write a balanced equation for the acid-base reaction that could, in principle, occur. Using Table 16.2, decide whether the equilibrium lies predominantly to the right or to the left.Ammonium chloride and sodium dihydrogen phosphate, NaH2PO4, are mixed in water. Write a balanced equation for the acid-base reaction that could, in principle, occur. Using Table 16.2, decide whether the equilibrium lies predominantly to the right or to the left.For each of the following reactions, predict whether the equilibrium lies predominantly to the left or to the right. Explain your predictions briefly. (a) NH4+(aq) + Br(aq) NH3(aq) + HBr(aq) (b) HPO42(aq) + CH3CO2(aq) PO43(aq) + CH3CO2H(aq) (c)[Fe(H2O)6]3+(aq) + HCO3(aq) [Fe(H2O)5(OH)]2+(aq) + H2CO3(aq)For each of the following reactions, predict whether the equilibrium lies predominantly to the left or to the right. Explain your predictions briefly. (a) H2S(aq) + CO32(aq) HS(aq) + HCO3(aq) (b) HCN(aq) + SO42(aq) CN(aq) + HSO4(aq) (c) SO42(aq) + CH3CO2H(aq) HSO4(aq) + CH3CO2(aq)Equal molar quantities of sodium hydroxide and sodium hydrogen phosphate (Na2HPO4) are mixed. (a) Write the balanced, net ionic equation for the acid-base reaction that can, in principle, occur. (b) Does the equilibrium lie to the right or left?Equal molar quantities of hydrochloric acid and sodium hypochlorite (NaClO) are mixed. (a) Write the balanced, net ionic equation for the acid-base reaction that can, in principle, occur. (b) Does the equilibrium lie to the right or left?Equal molar quantities of acetic acid and sodium hydrogen phosphate (Na2HPO4) are mixed. (a) Write a balanced, net ionic equation for the acid-base reaction that can, in principle, occur. (b) Does the equilibrium lie to the right or left?Equal molar quantities of ammonia and sodium dihydrogen phosphate (NaH2PO4) are mixed. (a) Write a balanced, net ionic equation for the acid-base reaction that can, in principle, occur. (b) Does the equilibrium lie to the right or left?A 0.015 M solution of hydrogen cyanate, HOCN, has a pH of 2.67. (a) What is the hydronium ion concentration in the solution? (b) What is the ionization constant, Ka, for the acid?A 0.10 M solution of chloroacetic acid, CICH2CO2H, has a pH of 1.95. Calculate Ka for the acid.A 0.025 M solution of hydroxyl amine has a pH of 9.11. What is the value of Kb for this weak base? H3NOH(aq) + H2O() H3NOH+(aq) + OH(aq)Methylamine, CH3NH2, is a weak base. CH3NH2(aq) + H2O() CH3NH3+(aq) + OH(aq) If the pH of a 0.065 M solution of the amine is 11.70, what is the value of Kb?A 2.5 103 M solution of an unknown acid has a pH of 3.80 at 25 C. (a) What is the hydronium ion concentration of the solution? (b) Is the acid a strong acid, a moderately weak acid (Ka of about 105), or a very weak acid (Ka of about 1010)?A 0.015M solution of a base has a pH of 10.09 a) What are the hydronium and hydroxide ion concentrations of this solution? b) Is the base a strong base, a moderately weak base (Ka of about 105) or a very weak base (Kb of about 1010)?What are the equilibrium concentrations of hydronium ion, acetate ion and acetic acid in a 0.20 M aqueous solution of acetic acid?The ionizations constant of a very weak acid, HA is 4.0109.Calculate the equilibrium concentrations of H3O+, A and HA in a 0.040M solution of the acid.What are the equilibrium concentration of H3O+, CN and HCN in a 0.025 M solution of HCN? What is the pH of the solution?Phenol (C6H5OH) commonly called carbolic acid is a weak organic acid C6H5OH(aq)+H2O(l)C6H5O(aq)+H3O+(aq)Ka=1.31010 If you dissolve 0.195 g of the acid in enough water to make 125ml of solution. What is the equilibrium hydronium ion concentration? What is the pH of the solution?What are the equilibrium concentrations of NH3,NH4+ and OH in a 0.15M solution of ammonia? What is the pH of the solution?A hypothetical weak base has Kb=5.0104.Calculate the equilibrium concentrations of the base, its conjugate acid, and OH- in a 0.15M solution of the base.The weak base methylamine, CH3NH2, has Kb=4.2104. It reacts with water according to the equation. CH3NH2(aq)+H2O(l)CH3NH3+(aq)+OH(aq) Calculate the equilibrium hydroxide ion concentration in a 0.25 M solution of the base. What are the pH and pOH of the solution?Calculate the pH of a 0.12 M aqueous solution of the base aniline, C6H5NH2(Kb=4.01010). C6H5NH2(aq)+H2O(l)C6H5NH3+(aq)+OH(aq)Calculate the pH of a 0.0010 M aqueous solution of HF.A solution of hydrofluoric acid, HF, has a pH of 2.30. Calculate the equilibrium concentration of HF, F, and H3O+ and calculate the amount of HF originally dissolved per litre.Calculate the hydronium ion concentration and pH in a 0.20 M solution of ammonium chloride NH4Cl.Calculate the hydronium ion concentration and pH for a 0.015M solution of sodium formate NaHCO3.Sodium cyanide is the salt of the weak acid HCN. Calculate the concentrations of H3O+,OH,HCN and Na+ in a solution prepared by dissolving 10.8g of NaCN in enough water to make 5.00102mLof solution at 25 C.The sodium salt of propionic acid, NaCH3CH2CO2 is used as an antifungal agent by veterinarians. Calculate the equilibrium concentration of H3O+ and OH the pH for a solution of 0.10M NaCH3CH2CO2.Calculate the hydronium ion concentration and pH of the solution that results when 22.0mL of 0.15M acetic acid CH3CO2H is mixed with 22.0 mL of 0.15M NaOH.Calculate the hydronium ion concentration and the pH when 50.0mL of 0.40M NH3 is mixed with 50.0mL of 0.40 M HCl.For each of the following cases, decide whether the pH is less than 7 equal to 7 or greater than 7. a) Equal volumes of 0.01 M acetic acid CH3CO2H and 0.10M KOH are mixed. b) 25mL of 0.015M NH3 is mixed with 25mL of 0.015 M HCl. c) 150 mL of 0.20M HNO3 is mixed with 75 mL of 0.40 M NaOH.For each of the following cases, decide whether the pH is less than 7, equal to 7 or greater than 7. a) 25 mL of 0.45 M H2SO4 is mixed with 25mL of 0.90 M NaOH. b) 15 mL of 0.050M formic acid, HCO2H is mixed with 15 mL of 0.50M NaOH. c) 25mL of 0.15M H2C2O4 (oxalic acid) is mixed with 25mL of 0.30 M NaOH (Both H+ ions of oxalic acid are removed with NaOH).Oxalic acid, H2C2O4, is a diprotic acid. Write a chemical equilibrium expression for each ionization step.Sodium carbonate is a diprotic base. Write a chemical equilibrium expression for each of the two successive base reactions with water.Prove that Ka1 Kb2 = Kw for oxalic acid H2C2O4, by adding the chemical equilibrium expressions that corresponds to first ionization step of the acid in water with second step of the reaction of the fully deprotonated base, C2O42, with water.Prove that Ka3 Kb1 = Kw for phosphoric acid, H3PO4, by adding the chemical equilibrium expressions that corresponds to the third ionization step of the acid in water with the first of the three successive steps of the reaction of phosphate ion, PO43, with water.Sulphurous acid, H2SO3, is a weak acid capable of providing two H+ ions. (a) What is the pH of a 0.45M solution of H2SO3? (b) What is the equilibrium concentration of the sulphate ion SO32, in the 0.45M solution of H2SO3?Ascorbic acid (vitamin C, C6H8O6) is a diprotic acid (Ka1 = 6.8 105 and Ka2 = 2.7 1012). What is the pH of a solution that contains 5.0 mg of acid per millilitre of solution? Ascorbic acidHydrazine, N2H4, can interact with water in two steps. N2H4(aq) + H2O() N2H5+(aq) + OH(aq) Kb1 = 8.5 107 N2H5+(aq) + H2O() N2H62+(aq) + OH(aq) Kb2 = 8.9 1016 (a) What is the concentration of OH, N2H5+ and N2H62+ in a 0.010M aqueous solution of hydrazine? (b) What is the pH of the 0.010M solution hydrazine?Ethylene diamine, H2NCH2CH2NH2, can interact with water in two steps, forming OH in each step (Appendix I). If you have a 0.15 M aqueous solution of the amine, calculate the concentration of [H3NCH2CH2NH3]2+ and OH.Which should be stronger acid, HOCN or HCN? Explain briefly. (In HOCN, the H+ ion is attached to the O atom of the OCN ion)76PSExplain why benzene sulfonic acid is a Brnsted acid.The structure of ethylene diamine is illustrated in study question 76. Is this compound a Brnsted acid, a Brnsted base, a Lewis acid or a Lewis base, or some combination of these.Decide whether each of the following substances should be classified as a Lewis acid or a Lewis base. (a) H2NOH in the reaction H2NOH(aq)+HCl(aq)[H3NOH]Cl(aq) (b) Fe2+ (c) CH3NH2 (Hint: Draw the electron dot structure)Decide whether each of the following substances should be classified as a Lewis acid or a Lewis base. (a) BCl3 (Hint: Draw the electron dot structure) (b) H2NNH2, hydrazine (Hint: Draw the electron dot structure) (c) the reactants in the reaction. Ag+(aq) + 2 NH3(aq)Carbon monoxide forms complexes with low-valent metals. For example, Ni(CO)4 and Fe(CO)5 are well known. CO also forms complexes with the iron(II) ion in haemoglobin which prevents the haemoglobin from acting in its normal way. Is CO a Lewis acid or a Lewis base?Trimethylamine, (CH3)3N, is a common reagent. It interacts readily with diborane gas, B2H6. The latter dissociates to BH3, and this forms a complex with the amine; (CH3)3N BH3. Is the BH3 fragment a Lewis acid or a Lewis base?About this time, you may be wishing you had an aspirin. Aspirin is an organic acid with a Ka of 3.27 104 for the reaction. HC9H7O4(aq) + H2O() C9H7O4(aq) + H3O+(aq) If you have two tablets, each contains 0.325 g of aspirin (mixed with a neutral binder to hold the tablet together), and you dissolve then in a glass of water to give 225 mL of solution, what is the pH of the solution.Consider the following ions: NH4+, CO32, Br, S2, and ClO4. (a) Which of these ions in water gives an acidic solution and which gives a basic solution? (b) Which of these anions will have no effect on the pH of an aqueous solution? (c) Which ion is the strong base? (d) Write a chemical equation for the reaction of each basic anion with water.A 2.50 g sample of a solid that could be Ba(OH)2 or Sr(OH)2 was dissolved in enough water to make 1.00L of solution. If the pH of the solution is 12.61, what is the identity of the solid?In a particular solution, acetic acid is 11% ionized at 25 C. Calculate the pH of the solution and the mass of acetic acid dissolved to yield 1.00L of solution.Hydrogen, H2S, and sodium acetate, NaCH3CO2 are mixed in water. Using Table 16.2, write a balanced equation for the acid-base reaction that could in principle, occur. Does the equilibrium lie toward the products or the reactants?For each of the following reactions predict whether the equilibrium lies predominantly to the left or to the right. Explain your prediction briefly. (a) HCO3(aq) + SO42(aq) CO32(aq) + HSO4(aq) (b) HSO4(aq) + CH3CO2(aq) SO42(aq) + CH3CO2H(aq) (c) [Co(H2O)6]2+(aq) + CH3CO2(aq) [Co(H2O)5(OH)]+(aq) + CH3CO2H(aq)A monoprotic acid HX has Ka = 1.3 103. Calculate the equilibrium concentration of HX and H3O+ and the pH for a 0.010M solution of the acid.Arrange the following 0.10M solutions in order of increasing pH. (a) NaCl (b) NH4Cl (c) HCl (d) NaCH3CO2 (e) KOHm-Nitrophenol, a weak acid, can be used as a pH indicator because it is yellow at pH above 8.6 and colorless at pH below 6.8. If the pH of a 0.010M solution of the compound is 3.44, calculates its pKa.The butylammonium ion, C4H9NH3+, has a Ka of 2.3 1011. C4H9NH3+(aq) + H2O() H3O+(aq) + C4H9NH2(aq) a) Calculate Kb for the conjugate base, C4H9NH2 (butyl amine). b) Place the butylammonium ion and its conjugate base in Table 16.2. Name an acid weaker than C4H9NH3+ and a base stronger than C4H9NH3. c) What is the pH of a 0.015M solution of butylammonium chloride?The local anaesthetic novocaine is the hydrogen chloride salt of an organic base, procaine. C13H20N2O2(aq)+HCl(aq)[HC13H20N2O2]+Cl(aq) The pKa for novocaine is 8.85. What is the pH of a 0.0015M solution of novocaine?Pyridine is weak organic base and readily forms a salt with hydrochloric acid. C5H5N(aq)+HCl(aq)C5H5NH+(aq)+Cl(aq)PyridinePyridiniumion What is the pH of a 0.025 M solution of pyridinium hydrochloride [C5H5NH+]Cl?The base ethylamine (CH3CH2NH2) has a Kb of. A closely related base, ethanolamine(HOCH2CH2NH2), has a Kb of 3.2105. (a) Which of the two bases is stronger? (b) Calculate the pH of a 0.10M solution of the strong base?Chloroacetic acid, ClCH2CO2H, is a moderately weak acid (Ka=1.40103). If you dissolve 94.5 mg of the acid in water to give 125 ml of solution, what is the pH of the solution?Saccharin (HC7H4NO3S) is a weak acid with pKa = 2.32 at 25 C. It is used in the form of sodium saccharide, NaC7H4NO3S. What is the pH of a 0.01M solution of sodium saccharide at 25 C?Given the following solutions: (a) 0.1 M NH3 (b) 0.1 M Na2CO3 (c) 0.1 M NaCl (d) 0.1 M CH3CO2H (e) 0.1 M NH4Cl (f) 0.l MNH4CH3CO2 (g) 0.1 M NH4CH3CO2 (i) Which of the solutions are acidic? (ii) Which of the solutions are basic? (iii) Which of the solutions is most acidic?For each of the following salts, predict whether a 0.10 M solution has a pH less than, equal to, or greater than 7. (a) NaHSO4 (b) NH4Br (c) KClO4 (d) Na2CO3 (e) (NH4)2S (f) NaNO3 (g) Na2HPO4 (h) LiBr (i) FeCl3 Which solution has the highest pH? The lowest pH?Nicotine, C10H14N2, has two basic nitrogen atoms (Figure 16.12), and both can react with water. Nic(aq)+H2O(l)NicH+(aq)+OH(aq)NicH+(aq)+H2O(l)NicH22+(aq)+OH(aq) Kb1 is 7.0 107 and Kb2 is 1.1 1010. Calculate the approximate pH of a 0.020 M solution.101GQThe equilibrium constant for the reaction of hydrochloric acid and ammonia is 1.8 109 (page 726). Confirm this value.The equilibrium constant for the reaction of formic acid and sodium hydroxide is 1.8 1010 (page 726). Confirm this value.Calculate the pH of the solution that results from mixing 25.0 mL of 0.14 M formic acid and 50.0 mL of 0.070 M sodium hydroxide.To what volume should 1.00 102 mL of any weak acid, HA, with a concentration 0.20 M be diluted to double the percentage ionization?The hydrogen phthalate ion, C8HsO4, is a weak acid with Ka = 3.91 106. C8H5O4(aq)+H2O(l)C8H4O42(aq)+H3O+(aq) What is the pH of a 0.050 M solution of potassium hydrogen phthalate. KC8H5O4? Note: To find the pH for a solution of the anion, we must take into account that the ion is amphiprotic. It can be shown that, for most cases of amphiprotic ions, the H3O+ concentration is [H3O+]=Ka1Ka2 For phthalic acid, C8H6O4 is Ka1 is 1.12 103, and Ka2 is 3.91 106.107GQ108GQ109IL110IL111ILA hydrogen atom in the organic base pyridine, C5H5N, can be substituted by various atoms or groups to give XC5H4N, where X is an atom such as Cl or a group such as CH3. The following table gives Ka values for the conjugate acids of a variety of substituted pyridines. (a) Suppose each conjugate acid is dissolved in sufficient water to give a 0.050 M solution. Which solution would have the highest pH? The lowest pH? (b) Which of the substituted pyridines is the strongest Brnsted base? Which is the weakest Brnsted base?Nicotinic acid, C6H5NO2, is found in minute amounts in all living cells, hut appreciable amounts occur in liver, yeast, milk, adrenal glands, white meat, and corn. Whole wheat (lour contains about 60. 0g per gram of flour. One gram (1.00 g) of the acid dissolves in water to give 60. mL of solution having a pH of 2.70. What is the approximate value of Ka for the acid? Nicotinic acid114ILSulfanilic acid, which is used in making dyes, is made by reacting aniline with sulfuric acid. (a) Is aniline a Brnsted base, a Lewis base, or both? Explain, using its possible reactions with HCl, BF3, or other acid. (b) Sulfanilic acid has a pKa value of 3.23. The sodium salt of the acid, Na(H2NC6H4SO3), is quite soluble in water. If you dissolve 1.25 g of the salt in water to give 125 ml, of solution, what is the pH of the solution?Amino acids are an important group of compounds. At low pH, both the carboxylic acid group (CO2H) and the amine group (NHR) are protonated. However, as the pH of the solution increases (say, by adding base), the carboxylic acid proton is removed, usually at a pH between 2 and 3. In a middle range of pHs, therefore, the amine group is protonated, but the carboxylic acid group has lost the proton. (This is called a zwitterion.) At more basic pH values, the amine proton is dissociated. What is the pH of a 0.20 M solution of alanine hydrochloride, [NH3CHCH3CO2H]Cl?How can water be both a Brnsied base and a Lewis base? Can water be a Brnsted acid? A Lewis acid?The nickel(II) ion exists as [Ni(H2O)4]2+ in aqueous solution. Why is this solution acidic? As part of your answer, include a balanced equation depicting what happens when [Ni(H2O)6]2+ interacts with water.The halogens form three stable, weak acids, HOX. (a) Which is the strongest of these acids? (b) Explain why the acid strength changes as the halogen atom is changed.The acidity of the oxoacids was described in Section 16.9, and a larger number of acids are listed in the table below. (a) What general trends do you see in these data? (b) What has a greater effect on acidity, the number of O atoms bonded directly to the central atom E or the number of OH groups? (c) Look at the acids based on Cl, N, and S. Is there a correlation of acidity with the formal charge on the central atom, E? (d) The acid H3PO3 has a pKa of 1.8, and this led to some insight into its structure. If the structure of the acid were P(OH)3, what would be its predicted pKa value? Given that this is a diprotic acid, which H atoms are lost as H+ ions? The odd H3PO3Perchloric acid behaves as an acid, even when it is dissolved in sulfuric acid. (a) Write a balanced equation showing how perchloric and can transfer a proton to sulfuric acid (b) Draw a Lewis electron dot structure for sulfuric acid How can sulfuric acid function as a base?You purchase a bottle of water. On checking its pH, you find that it is not neutral, as you might have expected. Instead, it is slightly acidic. Why?123SCQ124SCQ125SCQConsider a salt of a weak base and a weak acid such as ammonium cyanide. Both the NH4+ and CN ions interact with water in aqueous solution, but the net reaction can be considered as a proton transfer from NH4+ to CN. NH4+(aq) + CN(aq) NH3(aq) + HCN(aq) (a) Show that the equilibrium constant for this reaction, Kact, is 1. Knet=KaKbKw where Ka is the ionization constant for the weak acid NH4+ and Kb, is the constant for the weak base CN. (b) Calculate Knet values fur each of the following, NH4CN, NH4CH3CO2, and NH4K Which salt has the largest value of Kact, and why? (c) Predict whether a solution of each of the compounds in (b) is acidic or basic. Explain how you made this prediction (Yon do not need a calculation to make this prediction.)You have a 0.30 M solution of formic acid (HCO2H) and have added enough sodium formate (NaHCO2) to make the solution 0.10 M in the salt. Calculate the pH of the formic acid solution before and after adding solid sodium formate.1. What is the pH of the solution that results from adding 30.0 mL of 0.100 M NaOH to 45.0 mL of 0.100 M acetic acid?
2.87
5.05
7.00
What is the pH of a buffer solution composed of 0.50 M formic acid (HCO2H) and 0.70 M sodium formate (NaHCO2)?Use the Henderson-Hasselbalch equation to calculate the pH of 1.00 L of a buffer solution containing 15.0 g of NaHCO3 and 18.0 g of Na2CO3. (Consider this buffer as a solution of the weak acid HCO3 and its conjugate base, CO32.)Using an acetic acid/sodium acetate buffer solution, what ratio of conjugate base to acid will you need to maintain the pH at 5.00? Describe how you would prepare such a solution.Calculate the pH of 0.500 L of a buffer solution composed of 0.50 M formic acid (HCO2H) and 0.70 M sodium formate (NaHCO2) before and after adding 10.0 mL of 1.0 M HCl.1. Which choice would be a good buffer solution?
0.20 M KCH3CO2 and 0.20 M CH3CO2H
0.20 M HCl and 0.10 M KOH
0.20 M CH3CO2H and 0.10 M HCO2H
0.10 HCl and 0.010 M KCl
2. If an acetic acid/sodium acetate buffer solution is prepared from 100. mL of 0.10 M acetic acid what volume of 0.10 M sodium acetate must be added to have a pH of 4.00?
100. mL
50. mL
36 mL
18 mL
3RC4. To prepare a buffer containing CH3CO2H and NaCH3CO2 and having a pH of 5, the ratio of the concentration of CH3CO2H to that of NaCH3CO2 should be about
1/1
1.8/1
1/1.8
5.0/1
The titration of 0.100 M acetic acid with 0.100 M NaOH is described in the text. What is the pH of the solution when 35.0 mL of the base has been added to 100.0 mL of 0.100 M acetic acid?Calculate the pH after 75.0 mL of 0.100 M HO has been added to 100.0 mL of 0.100 M NH3 (Figure 17.7).1. What is the pH after 25.0 ml of 0.100 M NaOH has been added to 50.0 ml of 0.100 M HCl?
1.00
1.48
7.00
13.00
2. What is the pH at the equivalence point in the titration of 25.0 mL of 0.090 M phenol (Ka = 1.3 × 10−10) with 0.108 M NaOH?
7.00
5.65
8.98
11.29
3RCThe barium ion concentration, [Ba2+], in a saturated solution of barium fluoride is 3.6 103M. Calculate the value of the Ksp for BaF2. BaF2(s) Ba2+(aq) + 2 F(aq)Calculate the solubility of AgCN in moles per liter and grams per liter. Ksp for AgCN is 6.0 1017.Calculate the solubility of Ca(OH)2 in moles per liter and grams per liter (Ksp = 5.5 105).Calculate the solubility of BaSO4 (a) in pure water and (b) in the presence of 0.010 M Ba(NO3)2. Ksp for BaSO4 is 1.1 1010.12. Calculate the solubility of Zn(CN)2 at 25°C (a) in pure water and (b) in the presence of 0.10 M Zn(NO3)2. Ksp for Zn(CN)2 is 8.0 ×10−12.
What is the Ksp expression for silver carbonate? (a) Ksp[Ag+][CO32] (b) Ksp[Ag+]2[CO32] (c) Ksp[Ag+][CO32]22. Using Ksp values, predict which salt in each pair is more soluble in water.
AgCl(Ksp ≡ 1.8 ×10−10) or AgCN(Ksp ≡ 6.0 ×10−17)
Mg(OH)2(Ksp ≡ 5.6 ×10−12) or Ca(OH)2(Ksp ≡ 5.5 ×10−5)
Ca(OH)2(Ksp ≡ 5.5 ×10−5)or CaSO4(Ksp ≡ 4.9 ×10−5)
What is the solubility of PbSO4 in water at 25C? (Ksp for PbSO42.5 108) (a) 2.5 108 M (b) 1.6 104 M (c) 6.3 1016 M4. What is the solubility of PbSO4 in water at 25°C if the solution already contains 0.25 M Na2SO4(Ksp for PbSO4 ≡ 2.5 ×10−8)
1.0 × 10−7 M
1.6 × 10−4 M
6.3 × 10−9 M
5RCSolid Pbl2 (Ksp = 9.8 109) is placed in a beaker of water. After a period of time, the lead(II) concentration is measured and found to be 1.1 103 M. Has the system reached equilibrium? That is, is the solution saturated? If not, will more Pbl2 dissolve?2CYU3CYU