Chemistry - Calcium Carbonate

Calcium carbonate is a really important chemical that is used in the manufacture of lots of everyday items. Luckily, there is plenty of it just lying around - it is the main chemical in chalk and limestone. It is used to make many objects that you see all the time and it is unlikely that you will ever go for one whole day of your life without coming across something that needs calcium carbonate for its manufacture.

The name tells you its chemical composition - it contains calcium, carbon and oxygen. A lot of the calcium carbonate is made by shell-building organisms (such as corals) and plankton . After the organisms die, they sink to the seafloor. Over time, layers of shells and sediment are cemented together and turn to rock, storing carbon in stone for millions of years in the form of limestones and chalk. Some limestones are made by chemical reactions in the sea, when the conditions are just right.

Quarrying of both limestone and chalk is carried out on a large scale in Britain. Some of the limestone and chalk is used for building but a lot of it goes to the manufacture of cement. There are a lot of environmental issues with both the quarrying and the processing of limestone and chalk but without the calcium carbonate that it provides, our world would be an incredibly different place. Test your knowledge of the chemistry and uses of this versatile and important chemical ...