What Are the Precautions when Contacting Soda Lime?

Jan. 14, 2021

Soda lime is a white or beige powder, loose and porous, a mixture of calcium oxide (CaO, about 75%), water (H₂O, about 20%), sodium hydroxide (NaOH, about 3%), and potassium hydroxide (KOH, about 1%).

It is mainly used as a desiccant (in which calcium oxide plays a drying role), and 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 acid gases, such as carbon dioxide and sulfur dioxide.

It is a misconception that soda lime is a mixture of sodium hydroxide and calcium oxide, probably from the "soda lime experiment", where calcium oxide is added to a solution of sodium hydroxide and heated to make soda lime. Soda lime can be made from both sodium hydroxide and calcium oxide, just instead, not both. Still, try to write a mixture of sodium hydroxide and calcium oxide when you take the test. Preparation of methane, lime in soda lime does not participate in the reaction, but lime can dilute the concentration of the mixture, so that the mixture is loose, so that the resulting methane is easy to escape, but also to reduce the role of solid NaOH at high temperatures with the glass, to prevent the bursting of the test tube. The water absorption of quicklime can prevent the deliquescence of NaOH. The role of soda lime in the preparation of methane is to provide the reactants NaOH and desiccant (CaO).

Soda Lime

Protective measures

Protective gear should be worn when exposed to large amounts of soda lime, and work clothes or work caps should be made of cotton or appropriate synthetic materials. Operators must wear work clothes, masks, protective glasses, rubber gloves, rubber aprons, long rubber boots and other labour protection equipment when working. Neutral and hydrophobic ointment should be applied to the skin. When in contact with flake or granular soda lime, the workplace should be ventilated and the maximum permissible concentration in indoor air is 0.5 mg/m3 (in NaOH) for China MAC and 2 mg/m3 for US ACGIH TLVC. hood-type electric air-fed filtered dust respirator must be worn when possible contact with its dust. If necessary, wear an air respirator. Operators must be specially trained and follow strict operating procedures. It is recommended that operators wear hood-type electric air-fed filtered dust respirators, rubber acid- and alkali-resistant clothing and rubber acid- and alkali-resistant gloves. Keep away from flammable and combustible materials. Avoid generating dust. Avoid contact with acids. Handle lightly to prevent damage to packaging and containers. Equipped with spill emergency handling equipment. Empty containers may have harmful residues. When diluting or preparing solutions, add alkali to water to avoid boiling and splashing.

The above information is provided by the soda lime supplier.