Potassium bicarbonate (also known as potassium hydrogen carbonate or potassium acid carbonate), is a colorless, odorless, slightly basic, salty substance. The US Food and Drug Administration (FDA) recognizes potassium bicarbonate as "generally recognized as safe".
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 toxic effects on plants (potassium bicarbonate has widespread use in crops, especially for neutralizing acidic soil, and is also under consideration as an organic fungicide), although there is no evidence of human carcinogenicity, no adverse effects of overexposure, and an undetermined LD50.
Potassium bicarbonate is very rarely found in its natural form, mineral called kalicinite.
It is used as a base in foods to regulate pH. It is a common ingredient in club soda, where it is used to soften the effect of effervescence.
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.