Colligative properties: How to find Molarity


The concentration of a solute is the amount of solute dissolved in a given quantity of solvent or solution.The quantity of solvent or solution can be expressed in terms of volume or in terms of mass or molar amount.


The molarity (denoted by M ) of a solution is the moles of solute in a liter of solution.

Molarity = moles of solute/ liters of solution

A solution can be prepared to a specified molarity by weighing out the calculated mass of solute and dissolving in enough solvent to form desired volume of solution.

Lets see a solved example;

Sample problem :0.20 mol of ethylene glycol dissolved in enough water to give 2. L of solution , find the molarity?

Solution :

step 1 : moles of solute are given 

step 2 : and volume of solution in liter is given

step 3 : use the formula Molarity = moles of solute/ liters of solution to find molarity

step 4 : Molarity = .2 / 2.0 L = 0.10 M