Chapter 3: Equipping a Home Chemistry Laboratory 21Glass tubing
An assortment of glass tubing is useful for constructing
various apparatuses, including gas-generating bottles,
distillation setups, and so on. Look for tubing with an outside
diameter of 5 mm, which is the size accepted by all but the
smallest-holed rubber stoppers. Glass tubing is available in
borosilicate (Pyrex) and standard flint glass. The former is
useful for its resistance to heat, but the latter is more generally
useful, because it can be bent, stretched, and otherwise
manipulated after being heated in a standard alcohol
lamp flame.
Stirring rods
Stirring rods are solid glass rods that are available in various
lengths and diameters. In addition to their nominal purpose,
stirring rods can be used to decant liquids from one container
to another without spillage, and to prevent boiling liquids from
“bumping.” Have several stirring rods available, and consider
buying rods that include a “rubber policeman” on one end.
(A rubber policeman is a rubber scraper that fits snugly on
the end of the stirring rod.) These are useful for scraping
crystals from the sides of flasks and beakers and for other
similar tasks. Choose the length and diameter of your stirring
rods according to the sizes of glassware you use. Rods much
smaller than 5 mm are relatively fragile, particularly longer
ones. I generally use stirring rods that are 5 mm in diameter
and 8" (200 mm) long.
Evaporating dishes
An evaporating dish is a shallow bowl, usually made of
porcelain or borosilicate glass. They are used for evaporating
the solvent from a sample, either in the open air at room
temperature or in a desiccator or an oven. The 75 mm porcelain
models are a good size for a home chem lab. You can substitute
a Pyrex saucer or similar heat-resistant container.
watch glasses
Watch glasses are round convex/concave glass plates that are
used as beaker covers and for evaporating solvent from small
samples. I keep on hand a couple of watch glasses in sizes that
fit my beakers. For covering a beaker, plastic film wrap works
just as well.
Crucibles
Crucibles are small ceramic or metal pots with lids, used
when you need to heat a sample to a very high temperature.
Although it’s often possible to reuse crucibles, you should
discard it if the reaction causes any staining or other noticeable
change. Fortunately, crucibles are cheap—at least the Chinese-
made ones are. I confess that I prefer those, because if I’m
going to ruin a crucible, I’d sooner ruin a $0.75 Chinese one
than a $5.00 U.S.-made Coors crucible.
mortar and pestle
A mortar and pestle is used to grind dry chemicals to a fine
powder. A laboratory mortar and pestle may be made of
ceramic or glass or such metals as stainless steel or nickel.
Many kitchen supply stores carry mortars and pestles intended
for kitchen use that are also fine for laboratory use (but use
them in one place or the other, NOT both). As a teenager, my
mortar and pestle looked very much like a 4" steel pipe cap
and a large steel bolt.AvTIDO OxIC DUST
Always wear splash goggles, gloves, and a respirator
when you use a mortar and pestle to grind chemicals. To
minimize the amount of dust that escapes into the air,
make a temporary cover with a sheet of thin cardboard
or heavy paper large enough to cover the mortar. Punch
a hole in the cardboard large enough to fit the pestle, and
keep the mortar covered as you grind the chemical. Wear a
respirator mask any time you grind a chemical.z