Hydrogencarbonate ion

The hydrogencarbonate ion, produced in nature by this reaction, is one of the main causes of temporary hardness in water. Carbon dioxide is fairly soluble in water, 1 cm dissolving 1.7 cm of the gas at stp. The variation of solubility with pressure does not obey Henry s law, since the reaction... 

The amount of carbonic acid present, undissociated or dissociated, is only about 1 of the total concentration of dissolved carbon dioxide. Carbonic acid, in l especi of its dissociation into hydrogen and hydrogencarbonate ions, is actually a stronger acid than acetic acid the dissociation constant is ... 

In liquid nitric acid, hydrogen bonding gives a loose structure similar to that of hydrogencarbonate ions. However, although pure nitric acid does not attack metals readily and does not evolve carbon dioxide from a carbonate, it is a conducting liquid, and undergoes auto-ionisation thus ... 

Figure 4.3 The HyiC-ATPase transport of H and 1C ions in the stomach. The H+ ions are derived from carbonic acid and the resultant hydrogencarbonate ion is transported out of the cell into the interstitial space and hence into the blood. The H ions are transported into the lumen of the stomach in exchange for ions, which reguires ATP hydrolysis. K ions are transported back into the lumen of the stomach along with Cl" ions.

The HCOj is transported out of the red cell via a transporter that transports the chloride ion into the erythrocyte. The reverse process occurs in the lungs the hydrogencarbonate is transported into the erythrocyte in exchange for the chloride ion. Within the cell, the hydrogencarbonate ion is converted to CO2, via the same enzyme. 

If there is an excess of free hydrogen ions in the body, they are immediately taken up by the hydrogencarbonate ions, to form weak carbonic acid which has no ill effects. 

If the alkalinity of the system is increased, hydrogencarbonate ions can react with free hydroxide ions to form carbonate ions and water. 

The slightly lower base strength of Type 2 strong base anion exchangers results in the relative affinity of hydroxide ion usually coming between that of fluoride ion and hydrogencarbonate ion. 

NaHC03 The reason it is important to know the formulas of the polyatomic ions is so that you can recognize the unique pattern of letters and subscript numbers for each ion quickly. When you know the characteristic letter pattern of the hydrogencarbonate ion, H-C-O-3, the formula, NaHC03, can be quickly separated into the two ions, Na+1 HC03 , and the name of the compound follows, sodium hydrogencarbonate. 

However, many natural waters (lakes, ponds and reservoirs) are basic due to the presence of dissolved solids. For example, water saturated with CO2 and limestone (calcium carbonate) at 25 °C contains a higher concentration of hydrogencarbonate ion than water saturated with CO2 alone, and is slightly basic with a pH of 8.3. 

The hydrogencarbonate buffer in blood would soon become exhausted if there was not a way for the body to get rid of waste. Excess carbon dioxide and excess acid are removed by the lungs and kidneys, respectively. In this way, the hydrogencarbonate ions in the blood are released to act as a buffer once again. 

Recent studies have shown that many ulcers are caused by a specific species of bacteria (Helicobacter pylori). The problem of excess acid can be solved in two ways removing the excess acid or deceasing production of acid. Substances that remove excess acid via neutralization are known as antacids. They are solids containing hydroxide, carbonate or hydrogencarbonate ions. Medicinal drugs that decrease acid production are known as acid-inhibitors, for example, Tagamet and Zantac. 

The carbonic acid molecules immediately dissociate in water to form hydrogencarbonate ions, HCO3, and oxonium ions, H30 ... 

Pure unpolluted rain Is acidic due to the presence of dissolved carbon dioxide which is in equilibrium with hydrogen and hydrogencarbonate ions. Acid rain is more acidic (lower pH) than carbonic acid due to the presence of sulfurous and sulfuric acids, which are stronger acids than carbonic acid. 

Other buffers often exhibita substantial UV absorption below 215 nm. However, for the normal UV detection range around 254 nm a large number of buffers is available. Acetate with its pK of 4.75 is probably the most popular buffer, since its pK is exactly intermediate between the first and second dissociation constants of phosphate. Ammonium hydrogencarbonate is a preferred buffer for the pH range around 9 to 10, since the buffering ranges of the ammonium ion (pK = 9.24) and the hydrogencarbonate ion (pK, = 10.25) overlap. 

The pH of blood in a healthy human being varies from 7.37 to 7.43. There are two buffer systems that help maintain the pH of blood relatively constant one arising from a carbonic acid/bicarbonate (hydrogencarbonate) ion equilibrium and another involving protonated and deprotonated forms of hemoglobin. 

In red blood cells, this reaction is catalyzed by the enzyme carbonic anhydrase. Aqueous carbonic acid then deprotonates to form bicarbonate (hydrogencarbonate) ion ... 

Note that not all carbon compounds are classified as organic compounds. The oxides of carbon and compounds containing carbonate and hydrogencarbonate ions are classed as inorganic compounds. 

This reaction is catalysed by the enzyme carbonic anhydrase. When the blood passes through the small blood vessels around our lungs hydrogencarbonate ions are rapidly converted to carbon dioxide and water. The carbon dioxide escapes into the lungs. 

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