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Dear Mr. Science, Soda lime scrubber that you use consists of calcium 
hydroxide AND SODIUM HYDROXIDE both of which are required for conversion 
of CO2 to calcium carbonate. Rod

On Mon, 4 Nov 1996, Mr. Dude wrote:

> At last, something I can definitively comment on...
> 
> Rich, scrubber is essentially granulated Calcium Hydroxide (CaOH2), the
> hydrated version of Calcium Oxide (Quicklime - CaO).  Quicklime absorbs CO2
> faster than Hydrated Lime, but is incredibly reactive in the presence of
> water, and can generate enough heat to melt damn near any plastic, and some
> metals when mixed with water.
> 
> Hydrated Lime absorbs ANY CO2 it comes in contact with, reacting with it on
> the molecular level to become Calcium Carbonate (Limestone - CaCO3).
> Limestone is what it starts out as, and Limestone is what it shall become.
> 
> Therefore, since the reaction takes place on the molecular level, there is
> NO transfer of CO2 within the body of the granule, except via microscopic
> holes in the granule itself.  Once a molecule of CO2 has reacted with a
> molecule of CaOH2 it becomes, once again, CaCO3, the Hydrogen atom is
> driven off, where is combines with O2 and becomes water vapor once again.
> 
> That is why you can throw you used Sofnolime in the ocean with no ill
> effects.  It simply absorbs CO2 from the water until it becomes Limestone
> again.
> 
> There is sooo much limestone in the world because of all the little
> critters throughout time that have taken CO2 out of the water, mixed it
> with Calcium and an Oxygen free-radical to produce nice little CaCO3
> shells.  When these critters die, they sink to the sea floor, eventually to
> get compressed over time, to form almost pure Calcium Carbonate.  Your
> marble table started out that way.
> 
> An important fact about Calcium Carbonate (Limestone) is that Calcium is
> the fourth most common element in the Earth's crust, comprising 3.2%.  Only
> Silicon, Aluminium, and Iron are present in greater quantities.
> 
> Lime (Calcium Oxide, or Calcium Hydroxide) is never found in a natural
> state, due to its inherent instability (it absorbs any CO2 present, and
> converts back to Calcium Carbonate).  It is a manufactured product made by
> "calcining" limestone.  Calcining is the process of heating a substance to
> a high temperature below the melting or fusing point, in this case, between
> 1,800 and 2,400 degrees Fahrenheit, causing loss of moisture, and
> oxidation.  The calcining process drives off molecules of CO2 from the
> limestone, leaving pure CaO - Calcium Oxide, or "QuickLime".
> 
> Calcium Oxide is the 5th most produced chemical in the United States, and
> is used for everything from Steel manufacturing, to rebreather divers.
> 
> I produced a documentary on Lime several years ago, so the above is your
> lesson for the day...
> 
> Kevin "Mr. Science"
> Heyydude.
> 
> 
> --
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> Send subscription/archive requests to `techdiver-request@terra.net'.
> 

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