What gas does limewater test for?

Limewater can be used to detect the presence of carbon dioxide, or CO₂. When air containing CO₂ is blown directly into the limewater, it forms calcium carbonate. This turns the liquid cloudy, showing that the gas is present.

Climate change scientists and researchers believe that lime could help counteract some of the problems facing the environment, according to The Guardian. Rising levels of acidity as a result of man-made carbon dioxide emissions could be counteracted by converting limestone to lime and introducing the lime to the ocean water. The reaction of the lime with carbon dioxide creates bicarbonate ions that could help the ocean water absorb more carbon dioxide.