Molarity Calculator

Calculate molar concentration from mass, molecular weight, and volume. Perfect for chemistry students and professionals.

Calculator

Molarity Formula

Molarity (M): M = (mass in g) / (molecular weight × volume in L)
Moles: n = mass / molecular weight
Molarity: M = n / V
Where: M = molarity, n = moles, V = volume in liters

Example

To prepare 500 mL of 0.1 M NaCl solution:

  • • Molecular weight of NaCl = 58.44 g/mol
  • • Volume = 0.5 L
  • • Mass needed = 0.1 × 58.44 × 0.5 = 2.922 g
  • • Dissolve 2.922 g NaCl in water and dilute to 500 mL

Frequently Asked Questions

What is molarity?

Molarity (M) is a measure of concentration that represents the number of moles of solute per liter of solution. It's one of the most common ways to express concentration in chemistry.

How do you calculate molarity?

Molarity = (moles of solute) / (liters of solution). You can also calculate it using: Molarity = (grams of solute) / (molecular weight × liters of solution).

What are the units of molarity?

Molarity is expressed in moles per liter (mol/L or M). For example, a 1 M solution contains 1 mole of solute per liter of solution.

What's the difference between molarity and molality?

Molarity (M) is moles per liter of solution, while molality (m) is moles per kilogram of solvent. Molarity changes with temperature due to volume changes, but molality doesn't.

How do you prepare a solution of known molarity?

Weigh the required amount of solute, dissolve it in a small amount of solvent, then dilute to the final volume. Use a volumetric flask for accurate volume measurement.

What is the relationship between molarity and normality?

Normality = Molarity × n, where n is the number of equivalents per mole. For acids, n is the number of H+ ions; for bases, n is the number of OH- ions.