Page 24 - Curriculum Visions Dynamic Book

Chlorates
When chlorine and a large amount of oxygen combine with a metal, the resulting substance is known as a chlorate. Compounds that include chlorates are useful because they decompose to release oxygen.
Potassium chlorate is used as the oxygen supply in fireworks and safety matches. Ammonium perchlorate is used in the booster rockets of the space shuttle.
Sodium and potassium chlorates are used as weedkillers. Sodium and calcium chlorates are also used as oxidising bleaches (see page 14).
 Potassium produces a characteristic lilac-coloured flame, showing that it has been used in this catherine wheel firework.
Potassium chlorate and fireworks Potassium chlorate is an excellent source of the oxygen needed for combustion in fireworks. In addition, by changing the metal ions in the chlorate, the colours characteristic of each metal can be produced, thus providing colour to the display. Strontium chlorate gives a red colour; copper chlorate yields blue; barium chlorate green; and sodium chlorate yellow.
Dangers of using chlorate compounds
The large amount of oxygen in chlorate compounds means that they can be potentially very inflammable, and in some cases even explosive.
Weedkillers containing chlorates will, for example, remain as a coating on the weeds they have killed. This is especially dangerous in dry climates
where there is always a risk of fire. It is also why some illegal explosives have been made using weedkillers.
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