Ch.17 - Aqueous Ionic Equilibrium

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Ch.17 - Aqueous Ionic Equilibrium

Problema 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?

Problema 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?

Problema 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?

Problema 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.

Problema 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

Problema 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?

Problema 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?

Problema 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

Problema 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

Problema 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

Problema 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

Problema 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

Problema 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

Problema 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

Problema 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

Problema 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?

Problema 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)?

Problema 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?

Problema 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.

Problema 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.

Problema 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

Problema 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

Problema 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

Problema 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

Problema 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

Problema 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

Problema 61a

The graphs labeled (a) and (b) show the titration curves for two equal-volume samples of monoprotic acids, one weak and one strong. Both titrations were carried out with the same concentration of strong base.

(i) What is the approximate pH at the equivalence point of each curve?

Problema 61b

(ii) Which graph corresponds to the titration of the strong acid and which one to the titration of the weak acid?

Problema 62

Two 25.0-mL samples, one 0.100 M HCl and the other 0.100 M HF, are titrated with 0.200 M KOH. a. What is the volume of added base at the equivalence point for each titration?

Problema 62b

Two 25.0-mL samples, one 0.100 M HCl and the other 0.100 M HF, are titrated with 0.200 M KOH. b. Is the pH at the equivalence point for each titration acidic, basic, or neutral?