Lime can be divided into quicklime and hydrated lime. The main component of quicklime is calcium oxide (CaO), and the white solid is fire-resistant and difficult to tolerate. It is obtained by calcining limestone with high (CaO) content in a ventilated lime kiln to above 900°C. It is water-absorbent and can be used as a desiccant. It is commonly used among Chinese people to prevent debris from regaining moisture. Reacts with water (and releases a lot of heat at the same time), or absorbs moisture in the humid air, that is, hydrated lime [calcium hydroxide Ca (OH) 2], also known as "slaked lime". Hydrated lime dissolves 1.56 grams in one liter of water (20°C). Its solution is called "lime water", which is alkaline and absorbs carbon dioxide in the air to form calcium carbonate precipitation. The chemical formula of quicklime: CaO Calcium oxide The chemical formula of hydrated lime: Ca(OH)2 Calcium hydroxide CaO H2O==Ca(OH)2 When water is added, the reaction will release a lot of heat. Although both of them contain calcium, their chemical properties are Not the same. According to this chemical reaction formula, it can be written as follows: quicklime adds water to become slaked lime