In moisture content calculation, what do W and D represent?

• A. W is original mass, D is dry mass
• B. W is dry mass, D is original mass
• C. W is mass of water, D is density
• D. W is weight of water, D is dry density

Answer: (A)

Moisture content is found by comparing the water in the sample to the dry solids left after drying. W represents the original moist weight of the sample, and D represents the oven-dried weight (the mass of the solids after all moisture has been removed). The water mass is W minus D, and the moisture content is (W − D) / D × 100%.

For example, if the sample weighs 150 g when moist and 130 g after drying, moisture content is (150 − 130) / 130 × 100% = 15.4%.

So W is the original moist mass and D is the dry mass.