[victer24]

Is there any life time for cyanide salt?

Which means after Three to four months, is that effectiveness of cyanide salt will reduce?

[Borek]

I believe on contact with air it can get oxidized (no idea to what) and less effective. That's what I was told many years ago by an entomologist using cyanide to kill insects.

[Zyklonb]

Hydrogen peroxide oxidizes cyanide to cyanate, so atmospheric oxygen may do the same.
Quote from Wikipedia:

KCN can be detoxified most efficiently with hydrogen peroxide or with a solution of sodium hypochlorite. Such solutions should be kept basic whenever possible so as to eliminate the possibility of generation of hydrogen cyanide:

KCN + H₂O₂ → KOCN + H₂O

http://en.wikipedia.org/wiki/Potassium_cyanide#Toxicity

[Babcock_Hall]

Oxidation sometimes uses a catalyst
http://www.sciencedirect.com/science/article/pii/S0304389404004546

Safe handling tips:
http://safety.chemistry.unimelb.edu.au/cyanide.php

[snorkack]

Can HCN be driven out by carbonic acid in air?
KCN+H2O+CO2=KHCO3+HCN?

[discodermolide]

Yes. But not in large quantities, enough to smell.

[Borek]

Yes. But not in large quantities, enough to smell.

If memory serves me well, HCN can't be smelled unless its concentration is way above the dangerous levels.

Sure, just because you can smell it above vial doesn't mean there is enough to kill you, still, if it can be smelled, it shouldn't be ignored.

[discodermolide]

I think it's like H₂S, it saturates the nasal receptors and above a given concentration you can't smell it any more, but that may also be because you are dead!

[victer24]

Thanks for your replies..

But your replies are suitable, when the potassium cyanide is kept in outside atmosphere.  (In this case also please let me know at what factor it will detoxified)

Lets say, if we place this salt in plastic closed container then what will be result after 4 to 6 months....

Thanks again..

[discodermolide]

No great change.

[Babcock_Hall]

"The smell of cyanide
Trained observers can detect 2 ppm HCN in air. The sense of smell fatigues easily and fails at higher concentrations. Some 20% of adults have a hereditary inability to detect the characteristic odour. Clearly the odour is not a reliable warning signal. Any odour of HCN in an open laboratory is a danger warning and indicates poor chemical technique."  (link previously given)

[victer24]

No great change.

Can u please explain scientifically....?