soda lime
Noun: * A solid, granular chemical mixture primarily composed of sodium hydroxide (NaOH) and calcium hydroxide (Ca(OH)₂). Its primary function is to absorb and chemically react with certain liquids and gases, most notably carbon dioxide (CO₂) and water vapor (H₂O).
Soda lime is used as a technical term in specific scientific, medical, and industrial contexts where gas scrubbing or drying is required. * In closed-circuit breathing systems, such as those used in anesthesia or underwater diving, soda lime absorbs the carbon dioxide exhaled by the patient or diver, allowing the remaining oxygen to be rebreathed. * The laboratory technician used soda lime in the desiccator to maintain a dry atmosphere for storing moisture-sensitive chemicals. * A common indicator for the exhaustion of soda lime is a color change from white to violet or pink.
- Chemical Reaction: The absorption process is not merely physical; it involves chemical reactions where carbon dioxide reacts with the hydroxides to form carbonates (e.g., sodium carbonate, calcium carbonate).
- Indicator Dyes: Commercial soda lime often contains a pH-sensitive dye (like ethyl violet) that changes color as the material becomes exhausted and its alkalinity decreases, signaling when it needs to be replaced.
- Safety Handling: Due to its highly caustic nature (from sodium hydroxide), soda lime must be handled with care to avoid skin burns or respiratory irritation from dust.
- Soda lime glass: A common type of glass made from silica, soda (sodium carbonate), and lime (calcium oxide).
- CO₂ absorbent / scrubber: A more general functional term for materials, including soda lime, used to remove carbon dioxide.
- Desiccant: A general term for a substance that absorbs moisture; soda lime can act as a desiccant but is more specialized for acid gas absorption.
- Carbon dioxide absorbent
- CO₂ scrubber (in specific contexts)
- Alkaline absorbent mixture
- Soda lime canister: The container or apparatus filled with soda lime, used in breathing systems.
- Exhausted soda lime: Soda lime that has been fully used and can no longer effectively absorb gases.
- a mixture of sodium and calcium hydroxides; absorbs liquids and gases