Hydrogen cyanide half-life

Very small changes in acidity greatly affect chemical reactions and the form of chemical species in solution. For example, the hydrolysis half-life of hydrogen cyanide is greater than 100,000 years at pH 4 but drops to about 10 years at pH 9.39... 

HCN is lighter than air and has a long half-life in air. However, in open spaces, HCN is rapidly dispersed and is diluted to nontoxie concentrations. Cyanide does not bind to soil or plant material, but can mix with water. Contaminated water can be treated with ozone, hydrogen peroxide, or ealeium/sodium hypochlorite bleach. Rescue personnel should wear boots, gloves, goggles, Ml protective clothes, and a self-contained positive pressure breathing apparatus as the potential for secondary contamination is high (AAR, 2000). 

Tabun has a good solubility in water. The hydrolysis rate is dependent on the pH value and also the temperature, but is always rapid. The products are phosphoric acid and hydrogen cyanide. The half-life for tabun in sea water at a temperature of 7oC is approximately 5 hours. It is important to note that there will always be a difference in the half-life for phosphor organic agents in fresh water compared to sea water. 

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