Potassium bicarbonate

Overview
Potassium bicarbonate (also known as potassium hydrogen carbonate or potassium acid carbonate), is a colorless, odorless, slightly basic, salty substance. The compound is used as a source of carbon dioxide for leavening in baking, extinguishing fire in powder fire extinguishers, acting as a reagent, and a strong buffering agent in medications. The US Food and Drug Administration (FDA) recognizes potassium bicarbonate as "generally recognized as safe". It is used as a base in foods to regulate pH.

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.

Physically, potassium bicarbonate occurs as a crystal or a soft white granular powder. It has a CAS No [298-14-6]. It is manufactured by reacting potassium carbonate with carbon dioxide and water:


 * K2CO3 + CO2 + H2O &rarr; 2 KHCO3

Potassium bicarbonate is used as a fire suppression agent ("BC powder") in some dry powder fire extinguishers, as the principal component of the Purple-K powder. It is the only dry chemical fire suppression agent recognized by the National Fire Protection Association for firefighting at airport crash rescue sites. It is about twice as effective in fire suppression as sodium bicarbonate.