Carbonic Acid
<h2 ><b >Carbonic acid</b> is the <a href="http://en.wikipedia.org/wiki/Organic_compound" title="Organic compound" >organic compound</a> with the <a href="http://en.wikipedia.org/wiki/Molecular_formula" title="Molecular formula" class="mw-redirect" >formula</a> H<sub >2</sub>CO<sub >3</sub>(equivalently OC(OH)<sub >2</sub>). It is also a name sometimes given to<a href="http://en.wikipedia.org/wiki/Solution" title="Solution" >solutions</a> of <a href="http://en.wikipedia.org/wiki/Carbon_dioxide" title="Carbon dioxide" >carbon dioxide</a> in <a href="http://en.wikipedia.org/wiki/Water(molecule)" title="Water (molecule)" class="mw-redirect" >water</a>, because such solutions contain small amounts of H<sub >2</sub>CO<sub >3</sub>. Carbonic acid forms two kinds of <a href="http://en.wikipedia.org/wiki/Salt(chemistry)" title="Salt (chemistry)" >salts</a>, the <a href="http://en.wikipedia.org/wiki/Carbonate" title="Carbonate" >carbonates</a> and the <a href="http://en.wikipedia.org/wiki/Bicarbonate" title="Bicarbonate" >bicarbonates</a>. It is a <a href="http://en.wikipedia.org/wiki/Weak_acid" title="Weak acid" class="mw-redirect" >weak acid</a>.</h2>
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<p >Carbonic acid is used in the making of <a href="http://en.wikipedia.org/wiki/Soft_drinks" title="Soft drinks" class="mw-redirect" >soft drinks</a>, inexpensive and artificially carbonated sparkling wines, and other bubbly drinks.
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<h2 >Role of carbonic acid in blood</h2>
<p >Carbonic acid is an intermediate step in the transport of CO<sub >2</sub> out of the body via <a href="http://en.wikipedia.org/wiki/Gas_exchange" title="Gas exchange" >respiratory gas exchange</a>. The hydration reaction of CO<sub >2</sub> is generally very slow in the absence of a catalyst, but <a href="http://en.wikipedia.org/wiki/Red_blood_cells" title="Red blood cells" class="mw-redirect" >red blood cells</a> contain <a href="http://en.wikipedia.org/wiki/Carbonic_anhydrase" title="Carbonic anhydrase" >carbonic anhydrase</a>, which both increases the reaction rate and dissociates a hydrogen ion (H<sup >+</sup>) from the resulting carbonic acid, leaving <a href="http://en.wikipedia.org/wiki/Bicarbonate" title="Bicarbonate" >bicarbonate</a> (HCO<sub >3</sub><sup >-</sup>) dissolved in the <a href="http://en.wikipedia.org/wiki/Blood_plasma" title="Blood plasma" >blood plasma</a>. This catalysed reaction is reversed in the lungs, where it converts the bicarbonate back into CO<sub >2</sub> and allows it to be expelled. This equilibration plays an important role as a <a href="http://en.wikipedia.org/wiki/Buffer_solution" title="Buffer solution" >buffer</a> in mammalian blood.<sup id="cite_ref-1" class="reference" ><a href="http://en.wikipedia.org/wiki/Carbonic_acid#cite_note-1" >[2]</a></sup>
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