Limestone and its uses

-Limestone is mainly made of calcium carbonate 

-Some types of limestone were formed from the remains of tiny animals and plants that lived in the sea millions of years ago 

-We dig limestone out of the ground in quarries all around the world. 

-Many important buildings are made of limestone, we can cut and shape the stone taken from the ground into blocks 

-These cam be palced one on top of the other, like bricks. We have used limestone in this way to make buildings for hundreds of years

- Powdered limestone can be heated at high temperatures with a mixture of sand and sodium carbonate (soda) to make glass 

-Powdered limestone csn be heated with powdered clay to make cement 

-cement powder, water, dand, and crushed rock mixed together makes a slow chemical reaction which forms concrete 

-CaCO3 is the chemical formula for limestone 

-When we heat limestone strongly it breaks down to form a substance called quicklime (calcium oxide-CaO). Carbon dioxide is also produced. This reaction is called thermal decomposition 

-To make lots of quicklime  this reaction is done in a furnace called a lime kiln. They kiln is filled with crushed limestone which is heated strongly using a supply of hot air . Quicklime comes out the bottom of the kiln, while waste gases leave through the top 

-Calcium carbonate -> (heat) calcium oxide + carbon dioxide 

                                               (quicklime)