Sample not dry

If a sample has not been thoroughly dried, the mass displayed by the balance will be the mass of the substance plus the mass of any liquid on it.

If the sample is a product of a reaction, one indication that it may be wet is if the percent yield of the reaction is greater than one hundred.

Another sign of a wet sample is that the mass displayed on the balance gradually falls. This happens because the liquid is evaporating.

Solids collected by suction filtration are often moist. After suction filtration, to further dry the sample, place it on a large piece of filter paper. Crush the sample with another piece of filter paper using your thumb (be sure to wear gloves if the liquid is hazardous), and allow the sample to dry in the air for several minutes before remeasuring its mass.

Video: Wet samples ( 5.72 M )