Topic 2 - Limestone

What is Limestone, marble and chalk made from?

Sea shells that have been buried in the ground.

The chemical name for these rocks is Calcium Carbonate

The chemical formula for these rocks is CaCO3

How is calcium carbonate useful?

We have to cut and quarry it out of the ground

thermally decompose it

add water and other materials to the resulting calcium oxide to make cement and concrete for building materials.

Here is a less visual explanation for those of you who are not visual learners.

1) Calcium Carbonate --> Carbon dioxide + Calcium Oxide

                CaCO3        -->          CO2            +        CaO

2) Calcium Oxide + Water --> Calcium Hydroxide

         CaO           +  H2O    -->     Ca(OH)2

3) Calcium Hydroxide + Carbon dioxide --> Water + Calcium Carbonate

          Ca(OH)2          +         CO2           -->  H2O  +        CaCO3

Thermal decomposition is heating something to break it down, in this case Calcium Carbonate into Calcium Oxide and Carbon dioxide. CaCO --> CaO + CO2.