MOLARITY

Molarity of a solution is expressed as mole per liter or as millimoles per milliliter. Molar is abbreviated as M and we talk molarity of a solution when we speak of its concentration. The molarity of solution is calculated from:

Example 1

Calculate the molarity of a solution containing 10.0 g H2SO4 diluted to 250 mL?

Solution

Count the formula weight of H2SO4

= (2x1.00) + (1x32.07) + (4x16.00)
= 98.07 g/mol

The moles of H2SO4
= 10.0 / 98.07
= 0.10 mol
= 100 mmol

Molarity of H2SO4
= 100 mmol / 250 mL
= 0.4 mmol/ml = 0.4 M