6. A buffer solution contains 0.120 moles of propionic acid, HC3H5O2, and 0.100 moles of sodium propionate, NaC3H5O2, in 1.00 L of solution. Ka = 1.32 x 10-5 a. What is the pH of this buffer? b. What is the pH of this buffer after the addition of 0.010 mol of NaOH? c. Beginning with the initial buffer from part a, what is the pH of the buffer after the addition of 0.010 mol of HBr?

6. A buffer solution contains 0.120 moles of propionic acid, HC3H5O2, and 0.100 moles of sodium propionate, NaC3H5O2, in 1.00 L of solution. Ka = 1.32 x 10-5 a. What is the pH of this buffer? b. What is the pH of this buffer after the addition of 0.010 mol of NaOH? c. Beginning with the initial buffer from part a, what is the pH of the buffer after the addition of 0.010 mol of HBr?

Chemistry: The Molecular Science

5th Edition

ISBN:9781285199047

Author:John W. Moore, Conrad L. Stanitski

Publisher:John W. Moore, Conrad L. Stanitski

Chapter15: Additional Aqueous Equilibria

Section: Chapter Questions

Problem 31QRT

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A buffer solution is prepared by dissolving 1.50 g each of benzoic acid, C6H5CO2H, and sodium benzoate, NaC6H5CO2, in 150.0 mL of solution. (a) What is the pH of this buffer solution? (b) Which buffer component must be added, and in what quantity, to change the pH to 4.00? (c) What quantity of 2.0 M NaOH or 2.0 M HCl must be added to the buffer to change the pH to 4.00?
A buffer solution with it pH of 12.00 consists of Na3PO4 and Na2HPO4. The volume of solution is 200.0 mL. (a) Which component of the buffer is present in a larger amount? (b) If the concentration of Na3PO4 is 0.400 M, what mass of Na2HPO4 is present? (c) Which component of the buffer must be added to change the pH to 12.25? What mass of that component is required?
A buffer is made up of 0.300 L each of 0.500 M KH2PO4 and 0.317 M K2HPO4. Assuming that volumes are additive, calculate (a) the pH of the buffer. (b) the pH of the buffer after the addition of 0.0500 mol of HCl to 0.600 L of buffer. (c) the pH of the buffer after the addition of 0.0500 mol of NaOH to 0.600 L of buffer.
Lactic acid (CH3CHOHCO2H) is found in sour milk, in sauerkraut, and in muscles after activity. (Ka for lactic acid = 1.4 104.) (a) If 2.75 g of NaCH3CHOHCO2, sodium lactate, is added to 5.00 102 mL of 0.100 M lactic acid, what is the pH of the resulting buffer solution? (b) Is the pH of the buffered solution lower or higher than the pH of the lactic acid solution?
A buffer solution is composed of 1.360 g of KH2PO4 and 5.677 g of Na2HPO4. (a) What is the pH of the buffer solution? (b) What mass of KH2PO4 must be added to decrease the buffer solution pH by 0.50 unit from the value calculated in part (a)?
A 0.4000 M solution of nitric acid is used to titrate 50.00 mL of 0.237 M barium hydroxide. (Assume that volumes are additive.) (a) Write a balanced net ionic equation for the reaction that takes place during titration. (b) What are the species present at the equivalence point? (c) What volume of nitric acid is required to reach the equivalence point? (d) What is the pH of the solution before any HNO3 is added? (e) What is the pH of the solution halfway to the equivalence point? (f) What is the pH of the solution at the equivalence point?
You place 1.234 g of solid Ca(OH)2 in 1.00 L of pure water at 25 C. The pH of the solution is found to be 12.68. Estimate the value of Ksp for Ca(OH)2.
Consider the titration of 100.0 mL of 0.100 M HCN by 0.100 M KOH at 25C. (Ka for HCN = 6.2 1010.) a. Calculate the pH after 0.0 mL of KOH has been added. b. Calculate the pH after 50.0 mL of KOH has been added. c. Calculate the pH after 75.0 mL of KOH has been added. d. Calculate the pH at the equivalence point. e. Calculate the pH after 125 mL of KOH has been added.
Consider 1.0 L of a solution that is 0.85 M HOC6H5 and 0.80 M NaOC6H5. (Ka for HOC6H5 = 1.6 1010.) a. Calculate the pH of this solution. b. Calculate the pH after 0.10 mole of HCl has been added to the original solution. Assume no volume change on addition of HCl. c. Calculate the pH after 0.20 mole of NaOH has been added to the original buffer solution. Assume no volume change on addition of NaOH.
Two acids, each approximately 0.01 M in concentration, are titrated separately with a strong base. The adds show the following pH values at the equivalence point: HA, pH = 9.5, and HB, pH = 8.5. (a) Which is the stronger acid, HA or HB? (b) Which of the conjugate bases, A or B, is the stronger base?
Marble is almost pure CaCO3. Acid rain has a devastating effect on marble statuary left outdoors. Assume that the reaction which occurs is CoCO3(s)+ H+(aq)Ca2+(aq)+HCO3(aq) Neglecting all other competing equilibria and using Tables 15.1 and 13.2, calculate (a) K for the reaction. (b) the molar solubility of CaCO3 in pure water. (c) the molar solubility of CaCO3 in acid rainwater with a pH of 4.00.
A buffer is composed of formic acid and its conjugate base, the formate ion. (a) What is the pH of a solution that has a formic acid concentration of 0.050 M and a sodium formate concentration of 0.035 M? (b) What must the ratio of acid to conjugate base be to have a pH value 0.50 units higher than the value calculated in part (a)?