Quicklime and Slaked lime
When we add water to quicklime it reacts to produce slaked lime. Slaked lime's chemical name is calcium hydroxide. This reaction gives out a lot of heat.
Calcium oxide CaO + Water H₂O ---> Calcium hydroxide Ca(OH)₂
We can dissolve a little calcium hydroxide in water, after filtering, thsi produces a colourless solution called lime water.
We use lime water to test for carbon dioxide. We do this by bubbling carbon dioxide through lime water. If the solution turns cloudy then co2 is present. This is becuase calcium carbonate is formed, which is insoluble in water.
Calcium hydroxide + carbon dioxide ---> calcium carbonate + water
Ca(OH)₂ + CO₂ ---> CaCO₃ + H₂O