| Harmful
and Toxic Chemicals |
| The
difference between a harmful chemical and a toxic one is a matter
of degree; chemicals which are particularly harmful being classified
as toxic. Harmful and toxic chemicals must laways be handled in
a fume cupboard with the glass front pulled down as far as is practicable
to ensure that a good air-flow. It is also essential to wear protective
gloves and take particular note of any special instructions about
disposal and what to do in case of spillage.
Examples
of harmful and toxic materials are aniline, bromine, chlorofrorm,
methanol and cyanide salts |
| Flammable
Chemicals |
| Many
solvents and reagents used in the laboratory are highly flammable
and so there should never be naked flames in placies where they
are being used. The heating of flammable materials should be carried
out using water baths, heating mantles or hot plates.
Examples
of highly flammable solvents are diethyl ether, petroleum ether,
toluene, acetone (propanone) and ethyl acetate (ethy ethanoate). |
| Corrosive
Chemicals |
| The
most commonly encountered corrosive materials are acids and alkalis
although many other types of chemical fall into this category. It
is essential to wear appropriate protective gloves when handling
corrosive material and if there is contact with the skin it should
be washed off immediately with plenty of water. It may also be necessary
to seek medical attention.
Examples
of corrosive materials are the mineral acids (hydrochloric, nitric,
sulphuric and phoshoric acids), strong alkalis such as sodium hydroxide
and potassium hydroxide. |
| Oxidising
Agents |
|
Oxidising agents are dangerous because they can cause fires if they
make contact with any combustable material, particularly if they
are disposed of carelessly.
Examples
of oxidising agents are potassium dichromate (VI), potassium manganate
(VII), concentrated nitric acid as well as hydrogen peroxide. |
| Explosive
Reagents |
|
Many substances are
explosion hazards because of their extreme reactivity with water.
Other compounds are explosive because they are unstable, particularly
if heated or when dry. When handling such chemicals it is essential
to use only small amounts and protect yourself with a face mask
and a safety screen.
Examples
of explosion hazards are the alkali metals sodium and potassium.
|
| Irritants |
|
Chemicals which can
irritate the eyes and or the skin should always be handled in fume
cupboards.
Examples
of irritants are acid chlorides, thionyl chloride as well as certain
chloro compounds.
|
