Tro - Chemistry: A Molecular Approach 4th Edition - Chapter 17

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Ch.17 - Aqueous Ionic Equilibrium

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Tro 4th Edition

Ch.17 - Aqueous Ionic Equilibrium

Problem 45
What mass of sodium benzoate should you add to 150.0 mL of a 0.15 M benzoic acid solution to obtain a buffer with a pH of 4.25? (Assume no volume change.)
Problem 46
Pick the stronger base from each pair. a. ClO₄^– or ClO₂^– b. Cl^– or H₂O c. CN^– or ClO^–
Problem 46
What mass of ammonium chloride should be added to 2.55 L of 0.155 M NH3 to obtain a buffer with a pH of 9.55? (Assume no volume change.)
Problem 47
A 250.0-mL buffer solution is 0.250 M in acetic acid and 0.250 M in sodium acetate. a. What is the initial pH of this solution? b. What is the pH after the addition of 0.0050 mol of HCl? c. What is the pH after the addition of 0.0050 mol of NaOH?
Problem 48a
A 100.0-mL buffer solution is 0.175 M in HClO and 0.150 M in NaClO. a. What is the initial pH of this solution?
Problem 48b
A 100.0-mL buffer solution is 0.175 M in HClO and 0.150 M in NaClO. b. What is the pH after addition of 150.0 mg of HBr?
Problem 48c
A 100.0-mL buffer solution is 0.175 M in HClO and 0.150 M in NaClO. c. What is the pH after addition of 85.0 mg of NaOH?
Problem 49
For each solution, calculate the initial and final pH after adding 0.010 mol of HCl: a. 500.0 mL of pure water b. 500.0 mL of a buffer solution that is 0.125 M in HC2H3O2 and 0.115 M in NaC2H3O2 c. 500.0 mL of a buffer solution that is 0.155 M in C2H5NH2 and 0.145 M in C2H5NH3Cl.
Problem 50
For each solution, calculate the initial and final pH after adding 0.010 mol of NaOH. a. 250.0 mL of pure water b. 250.0 mL of a buffer solution that is 0.195 M in HCHO₂ and 0.275 M in KCHO₂ c. 250.0 mL of a buffer solution that is 0.255 M in CH₃CH₂NH₂ and 0.235 M in CH₃CH₂NH₃Cl
Problem 51
A 350.0-mL buffer solution is 0.150 M in HF and 0.150 M in NaF. What mass of NaOH can this buffer neutralize before the pH rises above 4.00? If the same volume of the buffer were 0.350 M in HF and 0.350 M in NaF, what mass of NaOH could be handled before the pH rises above 4.00?
Problem 52
A 100.0-mL buffer solution is 0.100 M in NH₃ and 0.125 M in NH₄Br. What mass of HCl can this buffer neutralize before the pH falls below 9.00?
Problem 53a
Determine whether or not the mixing of each pair of solutions results in a buffer. a. 100.0 mL of 0.10 M NH₃; 100.0 mL of 0.15 M NH₄Cl
Problem 53b
Determine whether or not the mixing of each pair of solutions results in a buffer. b. 50.0 mL of 0.10 M HCl; 35.0 mL of 0.150 M NaOH
Problem 53c
Determine whether or not the mixing of each pair of solutions results in a buffer. c. 50.0 mL of 0.15 M HF; 20.0 mL of 0.15 M NaOH
Problem 53d
Determine whether or not the mixing of each pair of solutions results in a buffer. d. 175.0 mL of 0.10 M NH₃; 150.0 mL of 0.12 M NaOH
Problem 53e
Determine whether or not the mixing of each pair of solutions results in a buffer. e. 125.0 mL of 0.15 M NH₃; 150.0 mL of 0.20 M NaOH
Problem 54a,b,d
Determine whether or not the mixing of each pair of solutions results in a buffer. a. 75.0 mL of 0.10 M HF; 55.0 mL of 0.15 M NaF b. 150.0 mL of 0.10 M HF; 135.0 mL of 0.175 M HCl d. 125.0 mL of 0.15 M CH₃NH₂; 120.0 mL of 0.25 M CH₃NH₃Cl
Problem 54c
Determine whether or not the mixing of each pair of solutions results in a buffer. c. 165.0 mL of 0.10 M HF; 135.0 mL of 0.050 M KOH
Problem 54e
Determine whether or not the mixing of each pair of solutions results in a buffer. e. 105.0 mL of 0.15 M CH₃NH₂; 95.0 mL of 0.10 M HCl
Problem 55a
Blood is buffered by carbonic acid and the bicarbonate ion. Normal blood plasma is 0.024 M in HCO₃^- and 0.0012 M H₂CO₃ (pK_a1 for H₂CO₃ at body temperature is 6.1).
a. What is the pH of blood plasma?
Problem 55b
If the volume of blood in a normal adult is 5.0 L, what mass of HCl can be neutralized by the buffering system in blood before the pH falls below 7.0 (which would result in death)?
Problem 55c
Blood is buffered by carbonic acid and the bicarbonate ion. Normal blood plasma is 0.024 M in HCO₃^- and 0.0012 M H₂CO₃ (pK_a1 for H₂CO₃ at body temperature is 6.1).
c. Given the volume from part (b), what mass of NaOH can be neutralized before the pH rises above 7.8?
Problem 56
The fluids within cells are buffered by H₂PO₄^- and HPO₄^2- . b. Could a buffer system employing H₃PO₄ as the weak acid and H₂PO₄^- as the weak base be used as a buffer system within cells? Explain.
Problem 57
Which buffer system is the best choice to create a buffer with pH = 7.20? For the best system, calculate the ratio of the masses of the buffer components required to make the buffer: HC2H3O2/KC2H3O2, HClO2/KClO2, NH3/NH4Cl, or HClO/KClO.
Problem 58
Which buffer system is the best choice to create a buffer with pH = 9.00? For the best system, calculate the ratio of the masses of the buffer components required to make the buffer. HF/KF HNO₂/KNO₂ NH₃/NH₄Cl HClO/KClO
Problem 59a
A 500.0-mL buffer solution is 0.100 M in HNO₂ and 0.150 M in KNO₂. Determine if each addition would exceed the capacity of the buffer to neutralize it. a. 250 mg NaOH
Problem 59b
A 500.0-mL buffer solution is 0.100 M in HNO₂ and 0.150 M in KNO₂. Determine if each addition would exceed the capacity of the buffer to neutralize it. b. 350 mg KOH
Problem 59c
A 500.0-mL buffer solution is 0.100 M in HNO₂ and 0.150 M in KNO₂. Determine if each addition would exceed the capacity of the buffer to neutralize it. c. 1.25 g HBr
Problem 59d
A 500.0-mL buffer solution is 0.100 M in HNO₂ and 0.150 M in KNO₂. Determine if each addition would exceed the capacity of the buffer to neutralize it. d. 1.35 g HI
Problem 60
A 1.0-L buffer solution is 0.125 M in HNO₂ and 0.145 M in NaNO₂. Determine the concentrations of HNO₂ and NaNO₂ after the addition of each substance: a. 1.5 g HCl b. 1.5 g NaOH c. 1.5 g HI