40.0 mL of a 0.65 M solution of HF is titrated with 0.100 M NaOH. After 0.400 L of the NaOH solution has been added, the resultant solution is:

The solution is basic and after the equivalence point

Explanation:

HF reacts with NaOH as follows:

HF + NaOH → H₂O + NaF

1 mole of acid reacts per mole of base.

The solution of HF contains:

40.0mL = 0.0400L × (0.65mol / L) = 0.026 moles of HF,

The titration will reach equivalence point when you add 0.026 moles of NaOH. If more NaOH is added the solution will be basic because NaOH (A base) is in excess doing the solution basic.

Moles added of NaOH are:

0.400L × (0.100 mol / L) = 0.0400 moles of NaOH

As the addition of NaOH is > 0.026 moles,