Potassium bicarbonate
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| Potassium bicarbonate | |
|---|---|
| Image:Potassium bicarbonate.jpg | |
| General | |
| Systematic name | potassium hydrogen carbonate |
| Other names | potassium acid carbonate |
| Molecular formula | KHCO3 |
| Molar mass | 100.11 g/mol |
| Appearance | colorless crystals or white powder |
| CAS number | [298-14-6] |
| Properties | |
| Density and phase | 2.17 g/cm3, solid |
| Solubility in water | 32.2 g/100 ml (20°C) |
| Melting point | decomposes 100°C-200°C |
| Structure | |
| Crystal structure | monoclinic |
| Hazards | |
| MSDS | Potassium bicarbonate |
| Related compounds | |
| Other cations | sodium bicarbonate |
| Related compounds | potassium carbonate |
| Except where noted otherwise, data are given for materials in their standard state (at 25°C, 100 kPa) Infobox disclaimer and references |
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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 via electrolysis:
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]
[edit] 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.
