Soda lime

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Contents 1 Chemical components 2 Scrubber in a rebreather 3 Chemical reaction 4 See also 5 External links

Soda lime is a mixture of chemicals, used in granular form in closed breathing environments, such as general anaesthesia, submarines, rebreathers and recompression chambers, to remove carbon dioxide from breathing gases to prevent CO₂ retention and carbon dioxide poisoning.

It is made by treating slaked lime with concentrated sodium hydroxide solution.

[edit] Chemical components

The main components of soda lime are

• Calcium hydroxide, Ca(OH)₂ (about 75%),
• Water, H₂O (about 20%),
• Sodium hydroxide, NaOH (about 3%), and
• Potassium hydroxide, KOH (about 1%).

[edit] Scrubber in a rebreather

Exhaled gas must be passed through a "carbon dioxide scrubber" where the carbon dioxide is absorbed before the gas is made available to be breathed again. In rebreathers the scrubber is a part of the breathing loop. In larger environments, such as recompression chambers, a fan is used to pass gas through the canister.

[edit] Chemical reaction

1. CO₂ + H₂O → H₂CO₃
2. H₂CO₃ + 2NaOH → Na₂CO₃ + 2H₂O + Heat
3. Na₂CO₃ + Ca(OH)₂ → CaCO₃ + 2NaOH
4. Ca(OH)₂ (heat) → CaO + H₂O

[edit] See also

• Lithium hydroxide

[edit] External links

• Sofnolime Example of a commercial soda lime product that is used in diving and medicine