The heat energy makes the calcium carbonate molecule fall apart to produce calcium oxide and carbon dioxide. It must be an endothermic reaction because we had to heat it up to get it to work.
Calcium oxide is a white powder that is often called quick lime. If added to water, it makes calcium hydroxide, which is often called slaked lime. Here's the reaction:
This is a very exothermic - it can give out a dangerous amount of heat energy. The calcium hydroxide is an alkali because of the OH- ions in it. OH- is called a HYDROXIDE ion.
The reason for doing all of this is that farmers can put the slaked lime alkali on their fields if the soil there is too acidic for growing crops. The calcium hydroxide can neutralise the acidic soils. The moorland soils in this part of the world are naturally acidic.
