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Science

Chemicals in the lab and home

Hazards and hazard symbols

For the exam, you'll need to be able to recognise some of the hazard symbols used in chemistry and to explain what they mean. You may also be asked to give examples of chemicals that should be labelled with a particular hazard symbol, or suggest a suitable hazard symbol for a particular chemical.

Hazard symbols

The diagrams on this page show some of the common hazard symbols used in chemistry, and their meanings. These symbols may be in a triangle or a square, and a chemical container might be labelled with more than one hazard symbol.

Corrosive

Attacks and destroys living tissues, such as skin and eyes.

liquid dripping on hands in black on yellow background

Corrosive

Concentrated solutions of strong acids such as sulphuric acid would be labelled with the corrosive symbol. Concentrated solutions of strong alkalis such as sodium hydroxide would also be labelled this way. Anyone using a corrosive substance should wear gloves and eye protection, such as goggles or a face shield.

Irritant

Not corrosive but will make the skin red or blister.

black x on yellow background with a small 'i' in the bottom right corner

Irritant

The dilute solutions of acids and alkalis that you normally use at school would be labelled with the irritant symbol. Anyone using an irritant substance should wear eye protection such as goggles, and they should take care to wash any spills off their skin immediately.

Toxic

Can cause death, eg if swallowed, breathed in or absorbed by skin.

black skull and crossbones on yellow background

Toxic

Lead oxide and chromium oxide would be labelled with the toxic symbol. Anyone using a toxic chemical would need to take great care. They should wear gloves and eye protection, and they may wear a mask over their mouth and nose or handle the chemical in a fume cupboard.

Harmful

Similar to toxic substances but not as dangerous.

black x on yellow background with a small 'h' in the bottom right corner

Harmful

Copper(II) sulphate would be labelled with the harmful symbol. Anyone using a harmful substance should wear eye protection such as goggles, and they should take care to wash any spills off their skin immediately.

Highly flammable

Catches fire easily.

a black fire on yellow background

Highly flammable

Ethanol and propanone would be labelled with the highly flammable symbol. In addition to the normal precautions of wearing eye protection, anyone using a highly flammable substance should take care to keep it away from flames and sparks, and also from oxidising substances.

Oxidising

Provides oxygen to make other substances burn more fiercely.

an 'O' with a fire on top in black, on a yellow background

Oxidising

Potassium manganate(VII) would be labelled with the oxidising symbol. Oxidising substances do not burn themselves but they provide oxygen for flammable substances to burn. In addition to the normal precautions of wearing eye protection, anyone using an oxidising substance should take care to keep it away from flammable substances, including clothing.

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