Soda lime

Soda lime

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.

Two types of soda lime are available in India: one is the non-standard variety usually meant for use in laboratories, and the other is Soda Lime I.P. which is fit for use on humans.

While administering general anaesthesia, the patient's expired gases which contain carbon dioxide, are passed through a circle absorber filled with soda lime granules. Medical grade soda lime has indicators which change colour when the soda lime loses its carbon dioxide absorbing capacity.

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%).

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.

Chemical reaction

The overall reaction is:

CO2 + Ca(OH)2 → CaCO3 + H2O + heat (in the presence of water)

The reaction can be considered as a strong base catalysed, water facilitated reaction.

steps:

1) CO2 + H2O → CO2 (aq) (CO2 dissolves in water - slow and rate determining)

2) CO2 (aq) + NaOH → NaHCO3 (bicarbonate formation at high pH)

3) NaHCO3 + Ca(OH)2 → CaCO3 + H2O + NaOH (NaOH recycled to step 2) - hence a catalyst)

each mole of CO2 (44g) reacted produces one mole of water (18g)

ee also

* Lithium hydroxide

External links

* [http://www.apdiving.com/downloads/datasheets/pdf/sofnolime.pdf Sofnolime] Example of a commercial soda lime product that is used in diving and medicine


Wikimedia Foundation. 2010.

Игры ⚽ Нужна курсовая?

Look at other dictionaries:

  • soda lime — soda lime, adj. a mixture of sodium hydroxide and calcium hydroxide. [1860 65] * * * ▪ chemistry       white or grayish white granular mixture of calcium hydroxide with sodium hydroxide or potassium hydroxide. Soda lime absorbs carbon dioxide and …   Universalium

  • soda lime — n a granular mixture of calcium hydroxide with sodium hydroxide or potassium hydroxide or both used to absorb moisture and acid gases and esp. carbon dioxide (as in gas masks, in the rebreathing technique of inhalation anesthesia, and in oxygen… …   Medical dictionary

  • soda lime — n. a white, powdery mixture of sodium hydroxide and calcium oxide, used as a chemical reagent and as an absorbent for moisture and acid gases …   English World dictionary

  • soda lime — noun a mixture of sodium and calcium hydroxides; absorbs liquids and gases • Hypernyms: ↑mixture * * * ˈsoda lime 7 [soda lime] noun uncountable a chemical containing ↑ …   Useful english dictionary

  • soda lime — natrio kalkės statusas T sritis chemija apibrėžtis CaO ir NaOH arba KOH mišinys. atitikmenys: angl. soda lime rus. натриевая известь; натровая известь; натронная известь …   Chemijos terminų aiškinamasis žodynas

  • Soda-lime glass — Soda lime glass, also called soda lime silica glass, is the most prevalent type of glass, used for windowpanes, and glass containers (bottles and jars) for beverages, food, and some commodity items. Also Pyrex brand kitchen glassware manufactured …   Wikipedia

  • soda-lime glass —       most common form of glass produced. It is composed of about 70 percent silica (silicon dioxide), 15 percent soda (sodium oxide), and 9 percent lime (calcium oxide), with much smaller amounts of various other compounds. The soda serves as a… …   Universalium

  • soda-lime glass — noun Etymology: soda lime : a lime glass in which soda is used …   Useful english dictionary

  • soda-lime glass — silikatinis stiklas statusas T sritis chemija apibrėžtis Stiklas, kurio stiklodaris – SiO₂. atitikmenys: angl. glass; silicate glass; silicious glass; soda lime glass rus. силикатное стекло; стекло …   Chemijos terminų aiškinamasis žodynas

  • soda lime — noun Date: 1862 a mixture of sodium hydroxide and slaked lime used especially to absorb moisture and gases …   New Collegiate Dictionary

Share the article and excerpts

Direct link
… Do a right-click on the link above
and select “Copy Link”