# Concentration

How much of a substance is dissolved in a given volume of solution. It is often measured in grams per dm3 or in moles per dm3.

Chemistry (school) · Part 05: Moles and calculations · Card 8 of 9 · Last updated 2026-10-19

## Analogy

Squash with a lot of syrup in a cup is more concentrated than squash with a little syrup.

## Example

**Concentration**

Concentration = mass / volume
10 g in 2 dm3
= 5 g/dm3

## In practice

A solution with 10 g in 2 dm3 has a concentration of 5 g/dm3.

## Practice

### Flashcards

- **How do you calculate concentration in g/dm3?** Mass of solute in grams divided by volume in dm3.

## Questions people ask

### How do you convert cm3 to dm3?

Divide by 1,000. There are 1,000 cm3 in 1 dm3, which is the same as one litre. So 250 cm3 is 0.25 dm3. Always convert before calculating concentration or moles in a solution, as formulae use dm3 as the unit of volume.

### What does a concentration of 2 mol/dm3 mean?

It means there are 2 moles of dissolved substance in every 1 dm3 of solution. Multiply concentration by volume in dm3 to get moles. So 0.5 dm3 of a 2 mol/dm3 solution contains 1 mole. A higher number means a more concentrated solution.

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