AP Chemistry Unit 8- Homework Problems Ka and Kb Acid & Base ...
AP Chemistry Unit 8- Homework Problems Ka and Kb Acid & Base ... AP Chemistry Unit 8- Homework Problems Ka and Kb Acid & Base ...
9. If 25 mL of weak base B was titrated as the graph below shows, calculate: a. Show the pH at the equivalence point b. Show the pH at the midpoint c. Calculate the original M of B d. Calculate K b of B Titration of 25 mL of ??? M weak base B with 0.50 M HCl HCl
Buffers 1. What is the definition of a buffer? 2. What kind of an acid and base are present in a buffer? 3. The K a of carbonic acid is 4.3x10 -7 . a. What is the pH of a solution that is 0.25 M H 2 CO 3 and 0.25 M NaHCO 3 ? b. What would the ratio of acid to base be if you wanted to buffer at exactly a pH of 6? 4. The K a of hydrozoic acid is 1.9x10 -5 . a. What is the pH of a solution that is 0.75 M HN 3 and 0.75 M N 3 -1 ? b. What would the ratio of acid to base be if you want to buffer exactly at a pH of 5? 5. The K b of aniline is 4.3x10 -10 . a. What is the pH of a solution that is 0.050 M C 6 H 5 NH 2 and 0.050 M C 6 H 5 NH 3 +1 ? b. What would the ratio of acid to base be if you want to buffer exactly at a pH of 9? 6. The K b of pyridine is 2x10 -9 . a. What is the pH of a solution that is 1.25 M C 5 H 5 N and 1.25 M C 5 H 5 NH +1 ? b. What would the ratio of acid to base be if you want to buffer exactly at a pH of 9? 7. Which of the following buffer systems would you choose if you want to buffer at a pH of 2? -1 a. HC 3 H 5 O 2 / C 3 H 5 O 2 K a = 1.35x10 -5 -1 b. HNO 2 / NO 2 K a = 7.2x10 -4 c. HIO / IO -1 K a = 2.3x10 -11 -1 d. H 3 PO 4 / H 2 PO 4 K a = 7.6x10 -3 Describe how to make the buffer so it is exactly at a pH of 2. 8. Lactic acid has a K a of 8.3x10 -4 . A buffer is made so that it is 0.50 M in HC 3 H 5 O 3 and 0.50 M in C 3 H 5 O 3 -1 . a. What is the pH of the buffer? b. What will the pH of the buffer be if 0.15 M of HCl are added? 9. Arsenous acid has a K a of 6.6x10 -10 . A solution is made so that it is 50 mL of 1.2 M in HAsO 2 . a. What is the pH of the solution? b. How many grams of NaAsO 2 must be added so the solution is a buffer at a pH of 10? Assume no change in volume. 10. Methylamine has a K b of 4.2x10 -4 . A buffer is made so that it is 0.75 M in CH 3 NH 2 and 0.75 M in CH 3 NH 3 +1 . a. What is the pH of the buffer? b. What will the pH of the buffer be if 0.25 M of HNO 3 are added? 11. Quinoline has a K b of 6.3x10 -10 . A solution is made so that it is 250 mL of 1.75 M C 9 H 7 N. a. What is the pH of the solution? b. How many grams of C 9 H 7 NHCl must be added so that the solution is a buffer exactly at a pH of 5? Assume no change in volume.
- Page 1 and 2: AP Chemistry Unit 8- Homework Probl
- Page 3 and 4: Acid-Base Interactions Strong-Stron
- Page 5: 4. Draw a titration curve of a weak
- Page 10: 3. For the reaction: NH 3 (aq) + H
9. If 25 mL of weak base B was titrated as the graph below shows, calculate:<br />
a. Show the pH at the equivalence point<br />
b. Show the pH at the midpoint<br />
c. Calculate the original M of B<br />
d. Calculate K b of B<br />
Titration of 25 mL of ??? M weak base B<br />
with 0.50 M HCl<br />
HCl
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