We are asked if the pH at the equivalence point in the HNO3 titration will be lower than the pH at the equivalence point in the CH3COOH titration where both were titrated with a 0.100 M solution of NaOH(aq).
1. Titration of 25.0 mL of 1.0 M HNO3 with 0.100 M NaOH solution
The reaction for this titration can be represented by:
HNO3 + NaOH → NaNO3 + H2O
In the reaction HNO3, a strong acid, will react with NaOH, a strong base to form a neutral solution.
At the equivalence point of the reaction, hydronium (H+) and hydroxide (OH-) ions will react to form water, leading to a pH of 7.
This is true for all strong acid and strong base reactions.
2. Titration of 25 mL of 1.0 M CH3COOH with 0.100 M NaOH
This reaction is a Weak Acid – Strong Base titration.
The reaction between HCH3COO and NaOH will be a double displacement reaction where H+ reacts with OH– and CH3COO– reacts with Na+.
The overall reaction is:
HCH3COO + NaOH→H2O + NaCH3COO
Recall that at the equivalence point of a titration: