Posted by Andrew on .
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.
Please help, I have no clue!!
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.