What amount of a substance is contained in 120 g of sodium hydroxide?

In order to find the amount of a substance, it is necessary to divide its mass by its molar mass.

Find the molar mass by adding up the molar mass of the atoms that make up the molecule.

Sodium hydroxide is composed of one sodium atom, one oxygen atom, and one hydrogen atom.

M NaOH = 23 + 16 + 1 = 40 grams / mol;

The amount of substance will be equal to:

N NaOH = 120/40 = 3 mol;