86 DIY Science: Illustrated Guide to Home Chemistry Experiments
- w how to treat minor burns, and always have a first-aid kit Kno
immediately available. - Know how to identify burns that require professional
treatment. (Any burn that is more severe than reddened skin
and very minor blistering should be examined by a physician.)
UISnG An ALCOHOL LAMP
For more than 100 years, alcohol lamps have been the
traditional heat source in home chemistry labs. Alcohol lamps
are inexpensive, easy to use, and provide a gentle heat suitable
for heating test tubes and other small containers. Follow these
guidelines when using an alcohol lamp:
- Use only alcohol in the lamp—either ethanol (ethyl alcohol) or
isopropanol (isopropyl alcohol) from the drug store. The 70%
solutions can be used, but the 91% or higher solutions provide
a cleaner, hotter flame. Never use acetone, gasoline, kerosene,
or other flammable solvents. - Make sure that the alcohol lamp has cooled completely before
you refill it. - After a refill, allow the wick to become completely saturated
with alcohol before you light the lamp. Otherwise, you’re
burning the wick instead of alcohol. - Adjust the exposed length of the wick to control the size of the
flame. Exposing more wick makes the flame larger. - When the wick becomes severely frayed, trim it off. Always
keep a spare wick or two on hand. - Extinguish the lamp by placing the cap (also called the snuffer)
over the wick.
FIGURE 5-16: Using a stirring
rod to avoid superheating
FIGURE 5-17: Heating a
test tube properly- ore the lamp with the cap in place to prevent evaporation. St
- If you need a higher temperature than the lamp provides, use
a blowpipe to force more oxygen into the flame, allowing it
to burn hotter. Place the tip of the pipe near the hottest part
of the flame (near the tip of the flame) and blow gently and
steadily through the blowpipe, directing the tip of the flame
at the object you want to heat. For most purposes, a length of
ordinary glass tubing makes a good blowpipe. If you need an
even hotter (but smaller) flame, draw the glass tubing (see
“Working with Glass Tubing,” later in this chapter) to provide a
smaller tip.
UGISnG A AS BURnER
Gas burners provide a much hotter, more intense flame than
alcohol lamps. Because they deliver more heat, gas burners
are better for heating larger volumes of liquids (although a hot
plate is usually an even better choice). Because the flame is very
hot—how hot exactly depends on the type of gas used and how
the burner is adjusted—gas burners are the best choice when you
need to heat a solid sample to a very high temperature.Formal laboratories use Bunsen or Tyrell burners connected
directly to natural gas taps, which is not practical for a home
laboratory. Fortunately, there are good and inexpensive
alternatives to having natural gas installed in your home lab. One
of the most convenient is a portable butane burner, shown in
Figure 5-18.FIGURE 5-18:
Adjusting the flame on a portable butane gas burner