A gram(g) is a metric unit of mass and was formally defined as the absolute weight of a volume of pure water equal to the cube of the hundredth part of a meter, and at the temperature of melting ice.

While a mole is the unit of measurement for amount of substance in the International System of Units.

**Formula to convert grams to moles.**

To convert g to moles, we divide the g by the molecular weight of the substance.

**Moles = Grams ÷ Molecular Weight**

**Example:**

Convert 20 grams of sodium to moles.

From the periodic table, we are told that the molecular weight of Na is 23grams, therefore, we will divide 20 g by 23 g.

**= 20 ÷** **23**

**= 0.87 moles.**