Potassium bicarbonate

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.

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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 → 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. [1]

History

The word saleratus, from Latin sal æratus meaning "aerated salt", was widely used in the 19th century for both potassium bicarbonate and sodium bicarbonate. The term has now fallen out of common usage.

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