Different units of measure may be used depending on the substance. Usually, the metric system, based on multiples of 10, is used to measure mass, volume, and length. Liters measure volume, the amount of space an object occupies.
Meters measure length.
Other units measure different properties of a substance. However, the number of grams in 1 mole varies greatly from substance to substance. For example, the molecular weight of calcium is 40, and 1 mole of calcium equals 40 grams. A milliequivalent is roughly equivalent to a milliosmole. Formulas are used to convert a measurement from one unit to another.