Soda lime is mainly used as a desiccant (calcium oxide plays a drying role). It can be used to dry neutral gases such as oxygen, and can also be used to dry alkaline gas ammonia. It can also be used to absorb acidic gases such as carbon dioxide and sulfur dioxide.

If only sodium hydroxide is present, this desiccant cannot be used at higher temperatures because sodium hydroxide can react with the glassware most commonly used in laboratories (the main component is silica) Corrosion instruments. A small amount of methane can be produced in the laboratory by heating soda lime and sodium acetate (sodium acetate) to produce sodium carbonate and methane.

Selection of desiccant:

The choice of desiccant depends not only on the properties of the desiccant but also on the properties of the material being dried. For example, concentrated sulfuric acid is an acid, so it cannot dry alkaline gases. ; In addition, concentrated sulfuric acid also has strong oxidizing properties, so it cannot be used to dry reducing substances such as HI, HBr, etc.

Liquid desiccants are generally installed in gas scrubbing bottles (gas enters from the long tube and exits from the short tube), while solid desiccant is installed in a drying tube or U-shaped tube.