1. Chemical Weathering-processes
Mr Boland

2. What have these two pictures got in common?

3. Both statue and headstone have been worn away by the rain.
This is a form of chemical weathering as a chemical action takes place between the rock and water.
Oxidation and carbonation are two forms of chemical weathering
Chemical Weathering

4. Why do you think the edge of this rock is red??
Why might it have broken??

5. Oxidation Oxidation is the rusting of rock
If you leave a bike in the rain it gets rusty
The same way, a rock containing Iron will get weaker and dissolve when it is raining.

6. Carbonation
When gas (Carbon Dioxide) mixes with rainwater it makes a weak carbonic acid.
This reacts with calcium carbonate in limestone causing the rock to dissolve.
Limestone is 80% calcium carbonate
This works the same way a tablet dissolves in a glass of water.

8. How does water travel through limestone
How does water travel through limestone? What might happen to limestone underground

9. Weathering – chemicals
There are also acids in the rain that can chemically eat away at rocks – especially rocks consisting of metal carbonates (such as chalk, limestone and marble).
Firstly, there is carbon dioxide gas which dissolves in rain to form weak carbonic acid. This very slowly eats away at certain rocks.
Secondly, there are nitrogen and sulphur oxides which produce much more acidic rain that can rapidly chemically dissolve the rocks.

10. Acid rain
Weathering is a natural process but humans are speeding this up by add car fumes and pollution to the air.
These fumes mix with the water in the air and falls as acid fain.
This can destroy parks, lakes and some building.