Question

1)A buffer solution that is 0.10 M sodium acetate and 0.20 M acetic acid is prepared. Calculate the initial pH of this solution.

The Ka for CH3COOH is 1.8 x 10-5 M. As usual, report pH to 2 decimal places.

*A buffered solution resists a change in pH.*

2)Calculate the pH when 28.8 mL of 0.035 M HCl is added to 100.0 mL of the above buffer.

3)Calculate how many mL of 0.100 M NaOH are needed to neutralize completely 55.0 mL of 0.0900 M HCl.

4)Calculate how many mL of 0.100 M NaOH are needed to neutralize completely 86.0 mL of 0.0400 M H2SO4 (forming Na2SO4 and water).

5)Calculate how many mL of 0.100 M NaOH are needed to neutralize completely 62.0 mL of 0.0600 M acetic acid.

Answer 1

For 1 use the Henderson-Hasselbalch equation to calculate pH.

2. Set up an ICE chart. The I line is what you start with in problem 1, the C line is what you're adding from problem 2, the E line is to be calculated and plugged into the HH equation and solve for the new pH.

3,4,5. mols acid = M x L
Convert mols acid to mols NaOH.
M NaOH = mols NaOH/L NaOH. You will have M and mols, solve for L and convert to mL.

Post your work if you get stuck.