# Avogadro constant

The number of particles in one mole of any substance. Its value is 6.02 x 10^23 per mole.

Chemistry (school) · Part 05: Moles and calculations · Card 4 of 9 · Last updated 2026-10-19

## Analogy

Just as 12 is the number in a dozen, this is the number in a mole.

## Example

**Counting particles**

Particles = moles x 6.02 x 10^23
0.5 mol of atoms
= 3.01 x 10^23 atoms

## In practice

Two moles of water contain 2 x 6.02 x 10^23 water molecules.

## Practice

### Flashcards

- **What is the Avogadro constant?** 6.02 x 10^23, the number of particles in one mole.

## Questions people ask

### Who was Avogadro?

Amedeo Avogadro was an Italian scientist in the early 1800s. He suggested that equal volumes of different gases at the same temperature and pressure hold the same number of particles. The constant was named in his honour, though it was measured long after he died.

### How do you use the Avogadro constant in a calculation?

Multiply the number of moles by 6.02 x 10^23 to get the number of particles. For 2 mol of water, you have 2 x 6.02 x 10^23 = 1.204 x 10^24 molecules. To go the other way, divide the number of particles by the constant to get moles.

## Related concepts

- [Mole](https://studyvisually.com/learn/science/chemistry-school/chemistry-school-part-5/chemistry-school-part-5-concept-3)
- [Moles from mass](https://studyvisually.com/learn/science/chemistry-school/chemistry-school-part-5/chemistry-school-part-5-concept-5)

Web page: https://studyvisually.com/learn/science/chemistry-school/chemistry-school-part-5/chemistry-school-part-5-concept-4
Study this card in the app: https://studyvisually.com/app/learn?category=chemistry-school&card=chemistry-school-part-5-concept-4