IMAGE. Heating an Erlenmeyer flask.
|
In Large Containers (Beakers or Erlenmeyer flasks):
Large containers should be supported above the flame by securing
the container on a ring stand. Wire gauze or a clay triangle may
be necessary to support the container. A clamp (or three-finger
clamp) can be used to secure the container on the support (see
IMAGE below).
In a Test Tube:
NEVER directly heat a solution in a test tube. Instead, set up a hot water bath to heat solutions in a test tube. Fill a beaker with water and gently heat (using procedure from
above) the water. Rest the test tube in the water. Do not leave
a test tube clamp on the test tube while it is in the water bath,
the clamp will get hot enough to burn the skin.
Why should a test tube never be directly heated? Answer
the sample is heated too fast -- due to the small volume involved in using
test tubes, it is easy to heat the liquid too fast. This can cause your sample
to burn or the test tube to crack.
bumping -- another consequence of using a Bunsen Burner to
heat a test tube is called "bumping". Liquid in the bottom of the tube is hottest and boils first. The bubbles of vapor can splatter the liquid out of the tube onto the surrounding area - or onto you.
|
