Molarity Calculator

Molarity (M) is moles of solute per liter of solution. It is the most common concentration unit in chemistry. A 1 M solution contains 1 mole of solute dissolved in enough solvent to make 1 liter of solution.

🧪 Solutions📐 M = n/V💧 Concentration

Moles of solute n (mol)

Volume of solution V (L)

Please enter valid values.

Formula & Reference

Variable	Symbol	Formula	Units
Molarity	M	M = n/V = m/(Mᵀ×V)	mol/L
Moles	n	n = M × V	mol
Volume	V	V = n/M	L
Mass	m	m = M × V × Mᵀ	g
1 M NaCl	58.44 g	per liter of solution	g/L

Step-by-Step Examples

Example 1

Prepare 1 M NaCl

Make 500 mL of 1.00 M NaCl (Mᵀ=58.44 g/mol).

n = M×V = 1.00×0.500 = 0.500 mol
mass = 0.500×58.44 = 29.22 g
Dissolve 29.22 g NaCl in water, dilute to 500 mL

✓ Weigh 29.22 g NaCl, dissolve and dilute to 500 mL

Example 2

Find Molarity

0.365 g HCl (M=36.46) dissolved in 100 mL solution.

n = 0.365/36.46 = 0.01001 mol
M = 0.01001/0.100 = 0.100 mol/L = 0.100 M

✓ 0.100 M HCl solution

Example 3

Find Volume

How many mL of 2.00 M H₂SO₄ contains 0.0500 mol?

V = n/M = 0.0500/2.00 = 0.0250 L
V = 25.0 mL

✓ Need 25.0 mL of the 2.00 M solution

Real-World Applications

🧪

Lab Solution Prep

Every quantitative experiment uses molarity to prepare precise concentrations.

💊

IV Fluids

Hospital saline (0.9% NaCl) is 0.154 M. Glucose drips are 5% (0.278 M).

🌊

Environmental Testing

Water quality standards are given in mol/L for heavy metals and pollutants.

📊

Titration

Titration uses known molarity of titrant to find unknown concentration of analyte.

Common Mistakes to Avoid

⚠️

Volume must be in liters

M = n/V where V is in LITERS. Convert mL to L: divide by 1000. 250 mL = 0.250 L.

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Mass vs moles

To use grams: first convert m to n using n = m/Mᵀ. Then M = n/V.

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Solution volume, not solvent volume

Molarity uses total SOLUTION volume, not just solvent added. Dissolve then dilute to final volume in volumetric flask.

Frequently Asked Questions

What is the difference between molarity and molality? ▾

Molarity (M) = mol/L solution. Molality (m) = mol/kg solvent. Molality does not change with temperature (volume does). Use molality for colligative properties.

How do I make a solution from a concentrated stock? ▾

Use C₁V₁ = C₂V₂. e.g., to make 100 mL of 0.1 M HCl from 12 M HCl: V₁ = (0.1×0.1)/12 = 0.83 mL of concentrated acid.

What is standard solution? ▾

A solution of precisely known concentration, prepared with an analytical balance and volumetric glassware. Used as a reference in titrations.

How does temperature affect molarity? ▾

Volume expands with temperature, so molarity decreases at higher temperature. Molality is temperature-independent.

What is the molarity of pure water? ▾

n/V = (1000 g/L ÷ 18.02 g/mol) = 55.5 mol/L. Pure water is 55.5 M.

Related Chemistry Calculators

Formula Explorer connections

Interpretation: molarity measures moles of solute per litre of final solution, not per litre of solvent. Assumption: volume must be expressed in litres and refers to the prepared solution at the stated temperature; solution volumes can change with mixing and temperature.

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