Concentration of Solutions

This lesson covers how to express and calculate the concentration of solutions as required by the Edexcel GCSE Combined Science specification (1SC0). You will learn to work in both g/dm³ (Foundation and Higher) and mol/dm³ (Higher tier only), and to convert between units.

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What Is Concentration?

Concentration tells you how much solute is dissolved in a given volume of solution.

• A concentrated solution has a large amount of solute in a given volume.
• A dilute solution has a small amount of solute in a given volume.

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Concentration in g/dm³

This is the simplest way to express concentration and is used at both Foundation and Higher tier.

$\text{concentration (g/dm}^3) = \frac{\text{mass of solute (g)}}{\text{volume of solution (dm}^3)}$concentration (g/dm3)=volume of solution (dm3)mass of solute (g)​

The Triangle

graph TD
    A["<b>mass (g)</b>"] --- B["<b>concentration<br/>(g/dm³)</b>"]
    A --- C["<b>volume<br/>(dm³)</b>"]
    B --- C
    style A fill:#f59e0b,color:#000,stroke:#d97706
    style B fill:#3b82f6,color:#fff,stroke:#2563eb
    style C fill:#3b82f6,color:#fff,stroke:#2563eb

To Find	Formula
Concentration	$c = \dfrac{m}{V}$c=Vm​
Mass	$m = c \times V$m=c×V
Volume	$V = \dfrac{m}{c}$V=cm​

Converting cm³ to dm³

1 dm³ = 1000 cm³

To convert cm³ to dm³: divide by 1000.