Corrosive A substance that may destroy living tissue on contact. It causes a burn.

13. Hazard Symbols Radiation These substances are radioactive. Radiation can damage cells and cause cancer. Harmful A substance that may cause harm in some way. Toxic A substance that is poisonous if swallowed or breathed in. It may even go through your skin! Environmental Hazard These substances damage or pollute the environment. Explosive A substance that may explode if it comes into contact with a flame or heat. It may also explode due to friction or shock. Biohazard These are living organisms that may cause infection. Oxidising This type of substance gives of a large amount of heat when in contact with other substances. Irritant A substance that may cause irritation to the skin, eyes or inside your body. Corrosive A substance that may destroy living tissue on contact. It causes a burn. Flammable A substance that can catch fire easily.

14. Neutralization A chemical reaction happens if you mix together an acid and a base. The reaction is called neutralisation, and a neutral solution is made if you add just the right amount of acid and base together. Metal oxides and metal hydroxides Metal oxides and metal hydroxides are two types of bases. For example copper oxide and sodium hydroxide. Here are general word equations for what happens in their neutralisation reactions with acids. metal oxide + acid → a salt + water metal hydroxide + acid → a salt + water Notice that a salt and water are always produced. The mixture usually warms up a little during the reaction, too. The exact salt made depends upon which acid and base were used. Carbonates and hydrogen carbonates Carbonates and hydrogen carbonates are two other types of base. They also make a salt and water when we neutralise them with acid. But this time we get carbon dioxide gas too. The reaction fizzes as bubbles of carbon dioxide are given off. This is easy to remember because we see the word 'carbonate' in the chemical names. These are the general word equations for what happens: acid + metal carbonate → a salt + water + carbon dioxide acid + metal hydrogen carbonate → a salt + water + carbon dioxide Using neutralisation Farmers use lime (calcium oxide) to neutralise acid soils. Your stomach contains hydrochloric acid, and too much of this causes indigestion. Antacid tablets contain bases such as magnesium hydroxide and magnesium carbonate to neutralise the extra acid. Bee stings are acidic. They can be neutralised using baking powder, which contains sodium hydrogen carbonate.