Calcium carbonate

Calcium carbonate is a chemical compound made of calcium and carbonate ions, with the chemical formula CaCO3. The elements involved are calcium (Ca), carbon (C), and oxygen (O). It is a common substance found as rock in all parts of the world, and is the main component of seashells, snails, and eggshell. 

Calcium carbonate is usually the main cause of hard water. It is used as a calcium supplement or as a treatment for antacid (brand name Tums), but too much can be bad for your health.

Calcium carbonate is found naturally as the following minerals and rocks:
 Aragonite
 Calcite
 Vaterite or (μ-CaCO3)
 Chalk
 Limestone
 Marble
 Travertine

Reactions with acids
Calcium carbonate reacts with strong acids (like hydrochloric acid) to make calcium salt, water, and carbon dioxide. It can also react with weak acids (like acetic acid) but less quickly. All of the rocks and minerals mentioned above will react with acids.

The balanced chemical equation of calcium carbonate and hydrochloric acid reaction is:

The word chemical equation for the hydrochloric acid reaction is:

While the balanced chemical equation of calcium carbonate and acetic acid reaction is:

And the word chemical equation for the acetic acid reaction is:

This is why a rock or mineral might need to be added with an acid to check there is calcium carbonate or not. If there is, then it will fizz and make carbon dioxide. But if it does not, then it will not fizz because there is no carbon dioxide forming.

Related pages
 Ocean acidification
 Gesso
 Cuttlefish
 Cuttlebone

Category:Geochemistry
Category:Calcium compounds
Category:Carbonates