Moles Calculator

The mole is the fundamental unit of amount in chemistry. One mole contains 6.022×10²³ particles. This calculator converts between mass (grams), moles, and number of particles.

⚗️ Stoichiometry📐 n = m/M🧪 General Chemistry

Mass m (g)

Molar Mass M (g/mol)

Please enter valid values.

Formula & Reference

Variable	Symbol	Formula	Units
Moles	n	n = m/M	mol
Mass	m	m = n × M	g
Particles	N	N = n × N_A	particles
Avogadro	N_A	6.022 × 10²³ mol^-1	mol⁻¹
Molar Mass	M	From periodic table	g/mol

Step-by-Step Examples

Example 1

Grams to Moles

How many moles in 54.06 g of water (M=18.02)?

n = m/M = 54.06/18.02
n = 3.000 mol

✓ 3.000 mol of H₂O

Example 2

Moles to Grams

What mass is 0.500 mol of NaCl (M=58.44)?

m = n×M = 0.500×58.44
m = 29.22 g

✓ 29.22 g of NaCl

Example 3

Molecules Count

How many molecules in 2 mol CO₂?

N = n×N₂ = 2×6.022×10²³
N = 1.204×10²⁴ molecules

✓ 1.204×10²⁴ molecules of CO₂

Real-World Applications

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Reaction Calculations

Every stoichiometry problem starts with converting grams to moles using molar mass.

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Drug Dosing

Pharmacists calculate active ingredient moles to ensure precise therapeutic dosing.

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Industrial Synthesis

Chemical engineers convert production quantities from kg to moles for reactor design.

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Teaching Chemistry

The mole concept is central to all quantitative chemistry education.

Common Mistakes to Avoid

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Dividing instead of multiplying (or vice versa)

n = m/M (divide mass by molar mass). m = n×M (multiply moles by molar mass). Remember: moles = grams ÷ g/mol.

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Wrong molar mass

Always calculate molar mass fresh from formula. H₂O = 18.02, not 18. Small errors compound in multi-step problems.

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Confusing atoms with molecules

N = n×N₂ gives molecules. For atoms in H₂O: multiply molecules by 3 (2H+1O). Be specific about what you are counting.

Frequently Asked Questions

Why is the mole such a large number? ▾

Avogadro number (6.022×10²³) was chosen so that 1 mole of carbon-12 atoms weighs exactly 12 grams. This bridges atomic mass units and lab-scale grams.

What is a millimole? ▾

1 mmol = 0.001 mol = 10⁻³ mol. Common in biochemistry and medicine where microgram quantities are used. 1 mmol glucose = 0.180 g.

How do I convert between moles and molarity? ▾

n (mol) = C (mol/L) × V (L). Molarity is moles per liter. To find moles in a solution: multiply molarity by volume in liters.

What is a gram-mole vs a pound-mole? ▾

A pound-mole contains 6.022×10²³×453.6 particles. Used in some engineering fields. Avoid mixing with standard mole in calculations.

Can you have a fraction of a mole? ▾

Yes. 0.5 mol = 3.011×10²³ particles. Moles are just a counting unit like dozen. 0.5 dozen = 6. 0.5 mol = 3.011×10²³.

Related Chemistry Calculators

Formula Explorer connections

Interpretation: This relationship converts chemical amount, mass, composition or balanced-equation ratios into a reaction quantity. Assumption: Use a balanced reaction, consistent units and the correct molar mass. Purity, side reactions and limiting reagents can change experimental results.

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