Question

When performing this experiment, a student mistakenly used impure KHP to standardize the NaOH solution. If the impurity is neither acidic nor basic, will the percent by mass of acetic acid in the vinegar solution determined by the student be too high or too low? Justify your answer with an explanation.

Answer 1

Think about it this way. Lets say you have x g of KHP. You calculate that to be y moles of KHP. Then you figure out the NaOH molarity to be z moles. Actually you have less than x g of KHP, and therefore less than y moles of KHP. So the molarity of NaOH will be less than z. And when you find the moles of acetic acid, what you obtain will be MORe than the actual value.