Show how would you prepare a solution of 500 mL of a 0.15 M acetate buffer, pH 4.6 based on one of the three methods illustrated in class and in the supplementary readings. You have available the following: 6 M HCl, 4 M acetic acid, solid sodium acetate, solid sodium hydroxide.Given

Question

Sodium acetate MW = 82
 HCl MW = 36.5
 Sodium hydroxide MW = 40
 pK for acetic acid dissociation = 4.76

Answer 1

Well, that's tough. I didn't attend any of your classes and I don't have the supplemental readings. But here is what I would do. a is acid and b is base.
pH = pKa + log (b)/(a)
4.6 = 4.76 + (a)/(b)
Solve for a/b. That's equation 1.

Then (a) + (b) = 0.15, That's eqn 2.

Solve for (a) and (b) by solving the two equations simultaneously. You know (b) and that is the sodium acetate. Weigh out the proper amount of NaAc. You now what you need for the acid. Use HAc. If it is 4M you know it has 4 mols/L. measure ou the volume you need to obtain that many mols in 500 mL. That's one way. Post your work if you get stuck.
(a) = ? M
(b) = ? M.

Then