By William Hirsch
Updated March 24, 2022
In chemistry, a mole represents a specific amount of substance equivalent to its atomic mass in grams. For instance, one mole of aluminum (atomic mass ≈ 26.98 g) contains 6.022 × 10²³ atoms, known as Avogadro’s number. Molarity (M) is the concentration of a solution expressed as moles of solute per liter of solution.
To find molarity, divide the number of moles by the volume in liters.
Example: 10.0 mol in 5.0 L → 10.0 mol ÷ 5.0 L = 2.0 M
To determine moles, multiply molarity by the volume in liters.
Example: 3.0 M in 2.0 L → 3.0 mol/L × 2.0 L = 6.0 mol
To compute the volume of a solution, divide the moles by the molarity.
Example: 6.0 mol at 3.0 M → 6.0 mol ÷ 3.0 mol/L = 2.0 L
These straightforward relationships enable quick conversions in laboratory calculations and theoretical work.
