Back to Ganoksin | FAQ | Contact

Shelf life of chemicals


#1

G’day Nick and others. There is no standard ‘use by’ time for many
thousands of chemicals, and it is really not practicable to offer
much in the way of advice. However, most inorganic chemicals are
stable provided the container has an air tight lid. The shelf life of
things like sodium chloride, ferrous sulphate, alum, sodium carbonate
and bicarbonate, sodium bisulphite and so on, is long. But many will
absorb moisture which helps destroy metal caps, and corrodable
things like corks.

 I am particularly interested in: 

Nitric acid (conc & dilute) ; Keep tightly stoppered in glass
or polythene and away from light. It is extremely corrosive.
Otherwise it will last years

Sulphuric acid (conc and dilute); The concentrated acid is avid for
moisture, and bottles must be kept airtight; it will corrode cork and
rubber. and is extremely corrosive. in good conditions it will last
years

Methylene Iodide (Iodomethane) Benzyl benzoate
Bromoform Monobromonapthalene Ether*
(Diethyl ether) Amyl acetate

All the above are volatile liquids, are flammable so must be well
stoppered, all will attack rubber and cork and all will soon
deteriorate in the presence of light, but are otherwise are fairly
stable; by that I mean there should be little change in several
years. All are poisonous and none of the vapours should be breathed.

*In the case of ether (diethyl ether); in the presence of a
little air and and light, it will react with air to form in time,
ether peroxides which are explosive. To guard against this
occurring, about 10 mls of strong ferrous sulphate solution in water
should always be present at the bottom of the bottle. As the
boiling point of ether is only 35C, it is extremely volatile and it’s
vapour is heavier than air and will therefore pool on the floor,
awaiting the slightest spark to cause a bad explosion…

Chemical solutions used in film development (black & white) are all
poisonous, and care should be taken not to get any on the hands or
body, as they are likely to cause skin irritation and dermatitis.
Wear a face shield and protective gloves. Since these chemicals are
used in dim lighting, it is well to wear a protective apron too.
Almost all will rapidly deteriorate, and won’t last more than a week,
except sodium or ammonium thiosulphate (‘Hypo’) which may be kept in
solution for months.

Just be careful. – Cheers for now, John Burgess; @John_Burgess2 of
Mapua, Nelson NZ


#2

John,

Thank you for your wonderfully detailed answer. It is much
appreciated.

I think it is time I got that donation off to Orchid and the
responses from you, Margaret and Tom have finally made me activate
myself and prepare that donation at long last! I have been meaning to
for ages, but…!

Kind regards - Nick