A biochemistry student wants to make an acidic buffer with pH of 4.20. They will start with 250 mL of a 0.5 M acetic acid (HC2H3O2) solution. Acetic acid has a pKa of 4.75. There are two ways to make this buffer. 1.1 The student is given 250 mL of a 0.5 M acetic acid (HC2H3O2) solution. What mass (in g) of sodium acetate (NaC,H¿O2: 82.03 g/mol) should they add to make this a solution with pH of 4.20? Round your answer to 3 significant digits. Assume that dissolving the solid will not change the volume of the solution. g of NaC,H;O2 1.2 The lab is currently out of sodium acetate. A friend suggests using sodium hydroxide. How does adding sodium hydroxide to an acetic acid solution make a buffer solution? Explain using a chemical equation. No calculation needed.

A biochemistry student wants to make an acidic buffer with pH of 4.20. They will start with 250 mL of a 0.5 M acetic acid (HC2H3O2) solution. Acetic acid has a pKa of 4.75. There are two ways to make this buffer. 1.1 The student is given 250 mL of a 0.5 M acetic acid (HC2H3O2) solution. What mass (in g) of sodium acetate (NaC,H¿O2: 82.03 g/mol) should they add to make this a solution with pH of 4.20? Round your answer to 3 significant digits. Assume that dissolving the solid will not change the volume of the solution. g of NaC,H;O2 1.2 The lab is currently out of sodium acetate. A friend suggests using sodium hydroxide. How does adding sodium hydroxide to an acetic acid solution make a buffer solution? Explain using a chemical equation. No calculation needed.

Principles of Modern Chemistry

8th Edition

ISBN:9781305079113

Author:David W. Oxtoby, H. Pat Gillis, Laurie J. Butler

Publisher:David W. Oxtoby, H. Pat Gillis, Laurie J. Butler

Chapter15: Acid–base Equilibria

Section: Chapter Questions

Problem 95AP

See similar textbooks

Similar questions

A buffer is prepared using the butyric acid/butyrate (HC4H7O2/C4H7O2)acid-base pair. The ratio of acid to base is 2.2 and Ka for butyric acid is1.54105. (a) What is the pH of this buffer? (b) Enough strong base is added to convert 15% of butyric acid to the butyrate ion. What is the pH of the resulting solution? (c) Strong acid is added to the buffer to increase its pH. What must the acid/base ratio be so that the pH increases by exactly one unit (e.g., from 2 to 3) from the answer in (a)?
Ka for formic acid is 1.7 104 at 25C. A buffer is made by mixing 529 mL of 0.465 M formic acid, HCHO2, and 494 mL of 0.524 M sodium formate, NaCHO2. Calculate the pH of this solution at 25C after 110 mL of 0.152 M HCl has been added to this buffer.
A good buffer generally contains relatively equal concentrations of weak acid and conjugate base. If you wanted to buffer a solution at pH = 4.00 or pH = 10.00, how would you decide which weak acidconjugate base or weak baseconjugate acid pair to use? The second characteristic of a good buffer is good buffering capacity. What is the capacity of a buffer? How do the following buffers differ in capacity? How do they differ in pH? 0.01 M acetic acid/0.01 M sodium acetate 0.1 M acetic acid/0.1 M sodium acetate 1.0 M acetic acid/1.0 M sodium acetate
Ammonia gas is bubbled into 275 mL of water to make an aqueous solution of ammonia. To prepare a buffer with a pH of 9.56, 15.0 g of NH4Cl are added. How many liters of NH3; at 25C and 0.981 atm should be used to prepare the buffer? Assume no volume changes and ignore the vapor pressure of water.
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.
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?
For the titration of 50.0 mL of 0.150 M ethylamine. C2H5NH2, with 0.100 M HCl, find the pH at each of the following points, and then use that information to sketch the titration curve and decide on an appropriate indicator. (a) At the beginning, before HCl is added (b) At the halfway point in the titration (c) When 75% of the required acid has been added (d) At the equivalence point (e) When 10.0 mL more HCl has been added than is required (f) Sketch the titration curve. (g) Suggest an appropriate indicator for this titration.
K4 for acetic acid is 1.7 105 at 25C. A buffer solution is made by mixing 52.1 mL of 0.122 M acetic acid with 46.1 mL of 0.182 M sodium acetate. Calculate the pH of this solution at 25C after the addition of 5.82 mL of 0.125 M NaOH.
Calculate the pH change when 10.0 mL of 0.100-M NaOH is added to 90.0 mL pure water, and compare the pH change with that when the same amount of NaOH solution is added to 90.0 mL of a buffer consisting of 1.00-M NH3 and 1.00-M NH4Cl. Assume that the volumes are additive. Kb of NH3 = 1.8 × 10-5.
A sodium hydrogen carbonate-sodium carbonate buffer is to be prepared with a pH of 9.40. (a) What must the [ HCO3 ]/[ CO32 ]ratio be? (b) How many moles of sodium hydrogen carbonate must be added to a liter of 0.225 M Na2CO3 to give this pH? (c) How many grams of sodium carbonate must be added to 475 mL of 0.336 M NaHCO3 to give this pH? (Assume no volume change.) (d) What volume of 0.200 M NaHCO3 must be added to 735 mL of a 0.139 M solution of Na2CO3 to give this pH? (Assume that volumes are additive.)