14. Oral solutions of Lipitor are often prepared in a buffer solution with a pH = 7.4. Which of the following buffer pairs would be the best choice for preparing this buffer solution? ☐ a. H3PO4 / H2PO4¯ ☐ b. H2PO4- /HPO4²- c. HPO42/PO4³- d. H3PO3 / H2PO3¯ e. H₂PO3/HPO3²- Ka = 7.5×10-3 Ka = 6.2×10-8 Ka = 3.6×10-13 Ka = 1.6×10-2 Ka = 7.0×10-7

14. Oral solutions of Lipitor are often prepared in a buffer solution with a pH = 7.4. Which of the following buffer pairs would be the best choice for preparing this buffer solution? ☐ a. H3PO4 / H2PO4¯ ☐ b. H2PO4- /HPO4²- c. HPO42/PO4³- d. H3PO3 / H2PO3¯ e. H₂PO3/HPO3²- Ka = 7.5×10-3 Ka = 6.2×10-8 Ka = 3.6×10-13 Ka = 1.6×10-2 Ka = 7.0×10-7

Chemistry by OpenStax (2015-05-04)

1st Edition

ISBN:9781938168390

Author:Klaus Theopold, Richard H Langley, Paul Flowers, William R. Robinson, Mark Blaser

Publisher:Klaus Theopold, Richard H Langley, Paul Flowers, William R. Robinson, Mark Blaser

Chapter14: Acid-base Equilibria

Section: Chapter Questions

Problem 100E: What mass of NH4Cl must be added to 0.750 L of a 0.100-M solution of NH3 to give a buffer solution...

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Similar questions

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)?
Malonic acid (HO2CCH2CO2H) is a diprotic acid. In the titration of malonic acid w ith NaOH, stoichiometric points occur at pH = 3.9 and 8.8. A 25.00-mL sample of malonic acid of unknown concentration is titrated with 0.0984 M NaOH, requiring 31.50 mL of the NaOH solution to reach the phenolphthalein end point. Calculate the concentration of the initial malonic acid solution. (Sec Exercise 113.)
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.
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
What mass of NH4Cl must be added to 0.750 L of a 0.100-M solution of NH3 to give a buffer solution with a pH of 9.26? (Him: Assume a negligible change in volume as the solid is added.)
Consider die titration of 50.0 mL of 0.10 M H3A (Ka1 = 5.0 104, Ka2 = 1.0 108, Ka3 = 1.0 1012) titrated by 0.10 M KOH. a. Calculate the pH of the resulting solution at 125 mL of KOH added. b. At what volume of KOH added does pH = 3.30? c. At 75.0 mL of KOH added, is the solution acidic or basic?
Repeat the procedure in Exercise 61, but for the titration of 25.0 mL of 0.100 M pyridine with 0.100 M hydrochloric acid (Kb for pyridine is 1.7 109). Do not calculate the points at 24.9 and 25.1 mL.
An aqueous solution contains dissolved C6H5NH3Cl and C6H5NH2. The concentration of C6H5NH2 is 0.50 M and pH is 4.20. a. Calculate the concentration of C6H5NH3+ in this buffer solution. b. Calculate the pH after 4.0 g NaOH(s) is added to 1.0 L of this solution. (Neglect any volume change.)
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.)