AQA Core Chemistry 1a (ii) - Products from Rocks

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AQA Core Chemistry 1a (ii) - Products from Rocks

Using Limestone.

The Mendip Hills and Yorkshire Dales are mainly made of a rock called limestone. When limestone is dug out of the ground it's great for building stuff like houses and churches from. You need limestone to male mortar, cement, concrete and glass too.

Limestone is Used as a Building Material.

1) Limestone is a grey/white colour. It's often formed from sea shells and although the original shells are mostly crushed, there are still quite a lot of fossiled shells remaining. 

2) It's quarried out of the ground but this causes environmental problems.

3) It's great for making into blocks for building with. Old building like cathedrals are often made purely from limestone blocks. It's also used for statues and fancy carved bits on buildings too.

4) Limestone's virtually insoluble in plain water, But acid rain is a big problem. The acid reacts with limestone and it eventually dissolves away.

5) Limestone can also be crushed up into chippings and used in road surfacing. 

Limestone is Mainly Calcium Carbonate.

1) Limestone is mainly calcium carbonate, CaCO3.

2) When it's heated it thermally decomposes to make calcium oxide (quicklime) and carbon dioxide.

Calcium Carbonate     ----->     Calcium Oxide    +     Carbon Dioxide

                  (Limestone)          Heat         (Quicklime)

      CaCO3(s)             ----->           CaO(s)         +            CO2 

3) When other carbonates are heated, they decompose the same way.

E.g sodium carbonate ----> sodium oxide + carbon dioxide (i.e. Na2CO3 ----> Na2O + CO2.).

Quicklime Reacts with Water to Produce Slaked Lime.

1) When you add water to quicklime you get slacked lime. Slaked lime is actually calcium hydroxide.

Quicklime + Water ----> Slaked Lime   OR   CaO + H2O ----> Ca(OH)2

2) Slaked lime is an alkali which can be used to neutralize acid soils in fields. Powdered limestone can be used for this too, but the advantage of slaked lime is it can work much faster.

3) Slaked lime can also be added to mortar.

Limestone is Used to Make Other Useful Things Too.

1) Powdered limestone is heated in a kiln with powdered clay to make cement.

2) Cement can be mixed with sand and water to make mortar. Mortar is the stuff you stick bricks together with. You can also use it to cover outside walls. 

3) Or you can mix it with sand, water and gravel to make concrete.

4) Limestone is also used to make glass. You just heat it with sand and sodium carbonate until it melts.

5) Concrete, cement and glass are used as building materials. But there are advantages and disadvantages to this.

Quarrying Limestone Makes a Right Mess of the Landscape.

Digging limestone out of the ground can cause environmental problems.

1) For a start it makes huge holes which permanently…


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