Chemistry Molarity Calculator: Step-by-Step Tutorial for Students

What is Molarity?

Molarity (M) is a measure of concentration, defined as moles of solute per liter of solution. It's the most common way to express concentration in chemistry.

The Molarity Formula

M = n/V

Where:

Step-by-Step Calculation

Problem: Calculate the molarity of a solution containing 5.85g of NaCl in 250mL of solution.

Step 1: Find molar mass of NaCl = 23 + 35.5 = 58.5 g/mol

Step 2: Calculate moles = 5.85g ÷ 58.5 g/mol = 0.1 mol

Step 3: Convert volume = 250mL = 0.25L

Step 4: Calculate molarity = 0.1 mol ÷ 0.25L = 0.4M

Dilution Calculations

For dilutions, use: M₁V₁ = M₂V₂

Example: How much water to add to 100mL of 2M HCl to make 0.5M?

2M × 100mL = 0.5M × V₂

V₂ = 400mL total (add 300mL water)

Practice with our Chemistry Calculator for step-by-step solutions.