Answer to Question #330794 in General Chemistry for Harry

Question

Why is the mass of the vinegar sample measures instead of its volume?

Answer 1

Mass measurements are generally better than volume measurements due to their accuracy. A mass measurement corresponds unambiguously to the amount of substance in the weighed sample.

The volume of a liquid, on the other hand, is dependant on its density. Density varies quite a bit with temperature, which means that 10 mL samples taken at 20⁰C and at 40⁰C will contain different amounts of substance and weigh differently.