Determine the pH of a solution that is prepared by mixing 100.0 mL of 0.125 M NaOH with 145 mL of 0.125 M CH3COOH (pKa = 4.75). Report your answer to 2 decimal places.

Question

Please help, I have no clue!!

Answer 1

1. Realize that NaOH and CH3COOH is the reaction of a strong base and a weak acid. Write and balance the equation. The products are CH3COONa and HOH.

2. Determine mols NaOH and mols CH3COOH. mols = L x M.

3. From the equation, determine mols CH3COONa formed. That is a salt. I haven't worked the problem but you PROBABLY will have an excess of CH3COOH which will make a buffer of CH3COOH and CH3COONa (a weak acid and its salt) and all of the NaOH will be used.

4. Then use the Henderson-Hasselbalch equation. pH = pKa + log [(base}/(acid)]

Show your work if you get stuck.

Answer 2

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