Potassium Acetate
Properties
| State | Solid (white crystalline, hygroscopic) |
| Color | White |
| Solubility | Very soluble in water (2530 g/L at 20 °C); soluble in methanol |
| Melting Point | 292 °C |
| Boiling Point | Decomposes before boiling |
About Potassium Acetate
Potassium acetate (KC2H3O2 or CH3COOK, 98.142 g/mol) is the potassium salt of acetic acid — a hygroscopic white powder that dissolves to about 2.5 kg per liter of water and gives a mildly basic solution because acetate is the conjugate base of a weak acid (Ka of acetic acid = 1.8 × 10^-5, so a 1 M acetate solution sits near pH 9.4). Two industries account for most of its tonnage. The first is airport runway de-icing: the FAA-approved Cryotech E36 product (50 percent KCH3COO solution) and several competing brands replaced glycol-based de-icers at most major airports because potassium acetate is biodegradable, non-corrosive to the aluminum alloys used in aircraft skins and landing gear, and effective down to about -26 °C. The second is molecular biology: the Birnboim-Doly alkaline lysis miniprep relies on a 5 M potassium acetate / glacial acetic acid solution at the neutralization step, where K+ co-precipitates with SDS, chromosomal DNA, and denatured protein, leaving plasmid DNA in solution. Smaller volumes go to food preservation and acidity regulation as E261, intravenous and oral potassium replacement in clinical hypokalemia (especially when chloride loading is contraindicated), buffer prep for chromatography, and as a catalyst in polyurethane foam manufacturing.
Where you'll encounter it
If you've ever run a plasmid miniprep, you've used potassium acetate — Solution III in the standard Qiagen/Macherey-Nagel kits is essentially 3 M potassium acetate at pH 5.5, and the snowy white precipitate that forms on the side of a 1.5 mL Eppendorf tube the moment you invert it is potassium dodecyl sulfate dragging chromosomal DNA and protein out of solution. If you've flown out of JFK, O'Hare, or Frankfurt in winter, the slippery wet film on the runway after a de-icing pass is a potassium acetate solution doing its work without eating the cadmium plating on landing gear. In the clinical lab, a potassium acetate IV piggyback is the alternative to KCl for a hypokalemic patient with metabolic alkalosis where adding more chloride would make things worse — the acetate metabolizes to bicarbonate and helps correct the acid-base imbalance at the same time it replenishes potassium.
Common Uses
- FAA-approved airport runway de-icer (Cryotech E36 and equivalents), non-corrosive to aluminum alloys
- Solution III in Birnboim-Doly alkaline-lysis plasmid DNA miniprep (3-5 M, pH 5.5)
- Food preservative and acidity regulator E261 in pickled and cured products
- IV potassium replacement for hypokalemia with metabolic alkalosis (chloride-sparing alternative to KCl)
- Acetate buffer component for HPLC and protein chromatography near pH 4-5
- Catalyst for polyurethane foam manufacturing and isocyanate trimerization
- Drying agent for ethanol via formation of the trihydrate
- Fire-extinguishing agent in Class K wet-chemical kitchen extinguishers
Safety Information
Low acute toxicity (oral LD50 rat ~3250 mg/kg). Mild eye irritant (GHS H319). OSHA: no specific PEL — handle as a general chemical dust under the 15 mg/m3 total nuisance-dust limit. Not classified as flammable, carcinogenic, or environmentally hazardous. Hygroscopic, so store in tight containers; concentrated solutions are mildly basic and can sting cuts but pose no serious chemical hazard. Standard lab PPE — safety glasses, gloves, lab coat — is sufficient.
This safety summary is for educational reference only and may not be complete. It is not a substitute for Safety Data Sheets (SDS), medical advice, or professional chemical safety guidance. Always consult appropriate SDS and qualified professionals before handling chemicals.