Hydrogen Carbonate

At room temperature ammonium bicarbonate is a white, crystalline powder with a slight odour of ammonia that can dissolve in water to give a mildly alkaline solution. It is however insoluble in acetone and alcohols. Ammonium bicarbonate decomposes at 36 to 60 °C into ammonia, carbon dioxide and water vapor in an endothermic process (as it is with many ammonium salts) and so causes a drop in the temperature of the water. When reacted with acids carbon dioxide is produced, while reactions with alkalis give ammonia.

Acid-base reactions
NaHCO₃ is a salt which consists of the ions Na⁺ and the bicarbonate anion, HCO₃-. It has a pKa of 6.3 in water which causes aqueous solutions to be mildly alkaline:
HCO₃- + H₂O H₂CO₃ + OH-

[edit] Reaction of sodium hydroxide with carbon dioxide
NaHCO₃ may be obtained by the reaction of carbon dioxide with an aqueous solution of sodium hydroxide :
The initial reaction produces sodium carbonate:
CO₂ + 2NaOH Na₂CO₃ + H₂O

Further addition of carbon dioxide produces sodium bicarbonate, which at sufficiently high concentration will precipitate out of solution:
Na₂CO₃ + CO₂ + H₂O 2NaHCO₃

Potassium bicarbonate is soluble in water, and is often found added to bottled water to affect taste; however, it is not soluble in alcohol. Decomposition of the substance occurs between 100°C and 120°C into K2CO3 (potassium carbonate), H2O (water), and CO2 (carbon dioxide). In concentrations greater than 0.5%, KHCO3 can have phytotoxic effects on plants (potassium bicarbonate has widespread use in crops, especially for neutralizing acidic soil), although there is no evidence of human carcinogenicity, no adverse effects of overexposure, and no LD50.