Adding sodium hydroxide, a strong base, will neutralize the acetic acid, a weak acid, producing sodium acetate, a salt, and water.
The balanced chemical equation will look like this
Depending on how many moles of acetic acid you had present in solution, and on how many moles of sodium hydroxide you add, the pH of the solution can have different values.
- Adding less moles of sodium hydroxide than of acetic acid
In this case, all of the sodium hydroxide will be consumed, but you'll still have acetic acid present in solution
- Adding equal numbers of moles of sodium hydroxide and acetic acid
At the equivalence point, all of the sodium hydroxide and all of the acetic acid present in the initial solution will be consumed. However, the reaction will produce sodium acetate, which will then react to produce
The pH of the solution will be higher than 7 because of the formation of hydroxide ions,
- Adding more moles of sodium hydroxide than of acetic acid
All of the acetic acid will be consumed. The remaining sodium hydroxide, being a strong base, will cause the solution's pH to be very high.