Question

Previously boiled, deionized water is unavailable. In a hurry to pursue the analysis, deionized water (not boiled) is added. How does this attempt to expedite the analysis affect the reported percent acetic acid in vinegar: too high, too low, or unaffected?

Answer 1

Answer:

The analysis is: acetic acid will be too low because of the acid that may still be in the water.  

Explanation:

We know that the amount of acetic acid in vinegar is determined by the volumetric titration of acetic acid with standardized NaOH solution; because it doesn't affect the number balance of hydronium and hydroxide ions.

This percent by mass of acetic acid will be too low because of the acid that may still be in the water.  

Now if the deionized water is contaminated in this case with carbonic acid, so there would be a consumption of a higher amount of NaOH for neutralization as a result. Therefore, the amount will depend on many factors.