1. Limestone
and its uses

2. What is limestone? It is a sedimentary rock
It was formed mainly from sea shells
It is the compound called calcium carbonate
It is a useful raw material

3. What can limestone be used for?
Building walls
Building houses
Limestone is also used to make cement and concrete
Neutralising excess acid in lakes or soils

4. More about limestone Limestone is dug up out of the ground in quarries
In Britain about 150 million tonnes of limestone are quarried each year
Limestone is the compound calcium carbonate
It’s formula is CaCO3
Limestone can be chemically changed into other things

5. Thermal decomposition reaction
Heating limestone
When limestone (calcium carbonate) is heated, it will break down (decompose)
When something breaks down with heat we call this reaction a ….
Thermal decomposition reaction
Calcium carbonate will have broken down into calcium oxide and carbon dioxide
We call calcium oxide quicklime

6. A word equation for this reaction
Calcium heat calcium carbon
Carbonate oxide dioxide

7. Reacting quicklime with water
Calcium oxide (quicklime) is a strong alkali
It reacts with water to form calcium hydroxide
Calcium hydroxide is also known as slaked lime

8. A word equation for this reaction
calcium water calcium
oxide hydroxide

9. Uses for slaked lime
To neutralise acidic soils, and to break up the soil so that plants can grow well
To neutralise lakes which have been polluted by acid rain

10. Another use for calcium hydroxide
Calcium hydroxide is also called limewater
Limewater is used to test for the presence of carbon dioxide gas
We breathe out a lot of carbon dioxide
If we blow through a straw into limewater it will change from clear to milky-white
The substance formed in this reaction is insoluble calcium carbonate

11. A word equation for this reaction
calcium carbon calcium water
hydroxide dioxide carbonate

12. These reactions all make up the
The Limestone Cycle
These reactions all make up the
limestone cycle.

13. The limestone cycle limestone carbon dioxide heat quicklime limewater
more
water
water
Slaked lime

14. Tasks: Use the worksheet called ‘The Limestone
Cycle’ to fill in the gaps and complete the
equations for the reactions of limestone.
Copy out The Limestone Cycle.
Answer questions 1-5 on the next worksheet
using the information given and your own
Knowledge. Afterwards copy out the
summary.

15. Questions on Limestone
HOMEWORK
Complete the worksheet on
Questions on Limestone
for next lesson.

16. This powerpoint was kindly donated to www.worldofteaching.com
is home to over a thousand powerpoints submitted by teachers. This is a completely free site and requires no registration. Please visit and I hope it will help in your teaching.