Question

How would these mistakes affect your results? Would it make the vinegar more or less acidic

1. Some of the added sodium hydroxide solution clung to the side of the flask and wasn't actually added to the diluted vinegar solution

2. You ran out of sodium hydroxide solution and when preparing a new batch you inadvertently made it more concentrated then the previous batch

3. There was a bubble in your pipette that you failed to notice when obtaining a vinegar sample for titration

4. You added base past the point where the indicator changed colors

Answer 1

Write the reaction between vinegar and NaOH

CH3COOH + NaOH --- >CH3COONa(aq) +

pH = pka + log ( [CH3COO-]/[CH3COOH])

This is Henderson-Hasselbach equation. This shows that when we have more the concentration of base the pH will be larger.

Less concentration of NaOH with acid has less pH.

1.) In this case, the concentration of NaOH is less than expected so the pH is also less. So it will make vinegar less acidic.

1. More NaOH is added and therefore the vinegar becomes less acidic.
2. volume of acid will be lower and it will make again more acidic as concentration = mol/ volume of solution.
3. When we add the base after the change in color will make vinegar more basic.