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also be quite flammable (red). Different suppliers may code the
same chemical differently. For example, Fisher Scientific codes
concentrated nitric acid yellow (oxidizer/reactant), and other
suppliers code it white (corrosive) or white with a stripe (corrosive
with special storage considerations; nitric acid reacts with
almost anything).
Storage codes may understate the danger. Violent reactions can
occur between two chemicals for which the color codes offer little
hint of danger. For example, potassium permanganate (yellow), a
strong oxidizer, bursts into flames if it contacts glycerol (green).
For that particular combination, yellow plus green equals extreme
red. Many suppliers code such chemicals individually with a STOP
icon, upraised palm icon, or similar indicator that some special
storage requirement applies to that chemical.
Conversely, storage codes may exaggerate the danger,
particularly for the small quantities typically stored and used in
home labs. For example, some suppliers color code 5% acetic
acid white (corrosive). That 5% acetic acid is exactly the same
chemical and in the same concentration as the white vinegar you
can buy at the supermarket.
Use the color coding on chemical bottles as a starting
point rather than as an absolute guide. Study the MSDS
for each chemical carefully, and pay particular attention to
listed incompatibilities with other chemicals. If you are storing
only small amounts of chemicals (say, 100 g or mL or less),
it’s probably sufficient just to segregate them on different
shelves or in different cabinets. If you are storing larger
quantities, pay correspondingly greater attention to
proper storage.
PDOPERR ISPOSAL OF USED
AnD UnnEEDED CHEMICALS
Many home chemists dispose of all chemical wastes simply
by flushing them down the drain with lots of water. That’s an
acceptable practice for many common laboratory chemicals, but
not for chemicals that are particularly toxic or hazardous to the
environment.
SAGEToR BINS
Heavy-duty Rubbermaid storage bins with latched lids
are excellent containers to use for small amounts of
chemicals. Buy several in appropriate sizes. Use a larger
one for general storage of chemicals that are color-coded
green. Use a smaller one color-coded white for acids,
a second white one for strong bases, a yellow one for
oxidizers/reactants, a red one for flammables, and a
blue one for poisons.LTEMOCK H UP
If there is even the slightest chance that children or
pets may gain access to your stored chemicals, secure
the storage cabinets and/or the lab itself with a sturdy
lock. Keep your chemicals locked up except when you’re
actually using them.z
Proper disposal of such hazardous chemicals is subject to an
incredible maze of federal, state, and local laws and regulations.
Fortunately, in practice many of these laws and regulations
apply only to commercial and industrial users. For example,
regulations for a particular chemical may come into play only if
you are disposing of 10 kilograms or more of that chemical per
month. Home chemists usually work with at most a few hundred
grams of any particular chemical, so check your local hazardous
waste disposal laws and regulations to determine the threshold
that applies.Before you choose a disposal strategy for your own home lab,
check the web site of your local or state environmental affairs
department to determine which laws and regulations apply to
you. Most communities provide some means for free disposal of
residential hazardous waste. Some communities hold periodic
hazardous waste days, when hazardous waste can be placed
separately at the curb for pickup. Others maintain hazardous
waste disposal centers where you can drop off containers of
hazardous waste. Take advantage of these services, and follow
any labeling or other requirements they specify.dISpoSAL of CommoN LABoRAToRy CHEmICALS
Safe disposal of chemicals raises two questions that are not
necessarily synonymous. First, you have to determine whether it
is safe to dispose of a particular chemical by a particular means.
Second, if it is safe, you have to determine whether it’s legal.Here are some general guidelines for disposing safely of common
laboratory chemicals. Note that these procedures describe my
own practices, which may or may not be lawful where you live.
Check before you use these procedures:- Small amounts of most flammable organic solvents (acetone,
alcohols, ethers, and so on) can safely be disposed of by
taking them outdoors and allowing them to evaporate.
Obviously, do this in an area that is not near a flame and not
accessible to children or animals. For larger amounts, place
the solvent in a sealed container labeled with its contents and
take it to the nearest hazardous waste disposal site.
DIY Science: Illustrated Guide to Home Chemistry Experiments