Moles in Solution — Concentration (g/dm³)

This lesson covers how to calculate concentration in g/dm³, as required by the AQA GCSE Combined Science Trilogy specification (8464). You will learn how to convert between mass, volume and concentration, and how to solve problems involving solutions.

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What Is Concentration?

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

The simplest unit is grams per cubic decimetre (g/dm³):

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

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Key Unit Conversions

From	To	Conversion
cm³	dm³	Divide by 1000
dm³	cm³	Multiply by 1000

$1 \text{ dm}^3 = 1000 \text{ cm}^3 = 1 \text{ litre}$1 dm3=1000 cm3=1 litre

Exam Tip (AQA 8464): The most common mistake is forgetting to convert cm³ to dm³. Always check the units in the question.

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The Concentration Triangle

graph TD
    A["<b>mass of solute (g)</b>"] --- B["<b>concentration (g/dm³)</b>"]
    A --- C["<b>volume (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