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Molarity: Formula, Examples & Calculator

Understand concentration, solve molarity problems step by step, and check your calculations with a free tool.

◎ Clear explanations◉ Worked examples▤ Practice problems⬇ Free resources

What is molarity?

Molarity measures the concentration of a dissolved solute in terms of the amount of solute per liter of final solution.

M = mol soluteL solution
Illustrated Molarity: Formula, Examples & Calculator study overview
IntoChemistry visual guide. Follow the worked examples below for the complete reasoning.

How to solve a molarity problem

  1. Identify the solute and the final solution volume.
  2. Convert milliliters to liters (divide mL by 1000).
  3. If given grams, divide by the solute molar mass to find moles.
  4. Divide moles by liters. Label the result mol/L or M.
  5. Round based on measured-data precision.

Visualize the formula

Molarity represented by a clear solute moles and solution liters diagram.
Molarity represented by a clear solute moles and solution liters diagram.

Worked examples

Worked example

Find molarity from moles and liters

  1. Given: 0.250 mol NaCl dissolved to make 0.500 L of solution.
  2. Apply M = n/V = 0.250 mol ÷ 0.500 L.
  3. Keep three significant figures.

Answer: 0.500 M NaCl.

Worked example

Find molarity from 5.85 g NaCl in 500.0 mL of solution

  1. Molar mass NaCl = 22.99 + 35.45 = 58.44 g/mol.
  2. Moles NaCl = 5.85 g ÷ 58.44 g/mol = 0.1001 mol.
  3. Volume = 500.0 mL × (1 L / 1000 mL) = 0.5000 L.
  4. Molarity = 0.1001 mol ÷ 0.5000 L.

Answer: 0.200 M NaCl (three significant figures).

Common mistakes

  • Using solvent volume instead of total solution volume.
  • Dividing grams directly by liters and calling the result molarity.
  • Forgetting to convert milliliters to liters.
  • Treating a calculator result as though it has unlimited significant figures.

Quick self-check

What happens to molarity if the solution volume doubles while moles stay constant?

The molarity is halved because M = n/V.

Interactive Molarity: Formula, Examples & Calculator Practice

Apply what you have learned using immediate feedback.

Calculator

Molarity Calculator

Molarity (M) = moles of solute ÷ liters of solution. Enter solution volume, not solvent volume.

For significant figures, report the result to the lesser of the input measurement precisions.