pH Exercise

CHEM 4400

Acid-Base Equilibria: a drink from the fountain of knowledge.

Acid base review, to equilibrate or not to equilibrate.

Ka for KOH is very large
Ka for acetic acid is 1.8 x 10-5

1. What is the pH of 500 mL of a 0.012 M solution of KOH?
2. What is the pH of a solution made by adding 15 ml of 2.0 M HCl to 485 mL of water.
2. What is the pH of a 0.015 M solution of acetic acid?

Hydroxide drops keep falling in my flask….
3. Draw the titration curve for the titration of a 0.1 M solution of acetic acid with 0.05 M sodium hydroxide.
4. Draw the titration curve for the titration of 0.1M glycine with 0.1M sodium hydroxide. Glycine has a pKa of 2.35 for the carboxylic acid group and a pKa of 9.78 for the amino group. The complete structure is in your book.

Buffy and the Vampire slayers:
5. You need to make a buffer for your biochemistry laboratory experiment that involves intestinal mucosa cells. These cells require a pH of 6.8 to survive. Give the complete directions (including substances, volumes and weights) for preparing 500 mL of this 0.2M buffer solution. The following Ka values may be useful:
H3PO4, Ka = 7.5 x 10-3 H2CO3, Ka = 4.6 x 10-7
NaH2PO4, Ka = 6.2 x 10-8 NaHCO3, Ka = 4.4 x 10-11
Na2HPO4, Ka = 4.8 x 10-13

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