Concentration: GCSE Chemistry Definition

What is concentration?

In GCSE Chemistry, concentration is the amount of a substance (solute) dissolved in a certain volume of liquid. Depending on your exam board and tier, the units of concentration are grams per cubic decimeter (g / dm³) or moles per cubic decimeter (mol / dm³). 

Concentration equation

The equation for concentration in grams per cubic decimeter (g / dm³) is:

The equation for concentration in moles per cubic decimeter (mol / dm³) is:

One of the most common mistakes in concentration calculations is not using the correct units for volume. Questions often give volume in cm³ but concentration requires dm³, so a conversion must be used:

Why is concentration important?

Concentration plays an important role in various chemical reactions, for example:

• In titrations, chemists measure the concentration of an unknown solution by reacting it with a solution of known concentration.

• Concentration can be used to control the rate of chemical reactions

  • High concentration means more particles in a given volume, which often leads to faster reaction rates. 

  • Low concentration means less particles in a given volume, which often leads to slower reaction rates. 

• In industry, concentration calculations can be performed before a chemical reaction is completed. This can potentially reduce the amount of chemicals needed and waste.

Concentration Revision Resources to Ace Your Exams

To explore concentration further, you should check out the revision notes on concentrations of solutions and practice our exam questions to ensure success. Flashcards on concentration are also a great way to revise this topic before an exam. 

Explore our GCSE Chemistry Revision Resources.