2.3 - The 'limestone reaction cycle' Flashcards
1
Q
What are the four substances in the limestone cycle?
A
- Calcium carbonate (limestone)
- Calcium oxide
- Calcium hydroxide
- Calcium hydroxide solution (limewater)
2
Q
How do you get from calcium carbonate to calcium oxide?
A
Heat it, which causes a thermal decomposition reaction. Carbon dioxide is given off
3
Q
How do you get from calcium oxide to calcium hydroxide?
A
Add a little water
4
Q
Why is calcium hydroxide useful? (4)
A
- It’s an alkali
- this means it can neutralise acids
- e.g, used by farmers to neutralise acidic soils
- e.g, used in industry to neutralise acidic gases
5
Q
How do you get from calcium hydroxide to calcium hydroxide solution?
A
Add more water and filter. Calcium hydroxide is not very soluble in water but dissolves slightly to make calcium hydroxide solution (limewater)
6
Q
How do you get from calcium hydroxide solution to make calcium carbonate?
A
Add carbon dioxide (this is the limewater test for carbon dioxide)
