Title: Determining boiling points with small samples'
1Determining boiling points with small samples.
2Determining boiling points with small samples.
- and The Semi-
- micro
Method
3Determining boiling points with small samples.
- The first segment is taking boiling points by the
micro method. - Several drops of sample will
- be required for this method.
4Place several drops in a 3 inch test tube and
invert a capillary tube into the sample.
- Fasten the sample along side a thermometer bulb.
5Clamp the assembly in the oil bath.
- Take care that the rubber ring is not touched by
the oil.
6Heat and stir until a rapid stream of bubbles is
coming from the tube.
- You are ABOVE the boiling point! Remove the
burner, BUT KEEP STIRRING!!!
7Continue to stir, and watch!! As the sample
cools, the stream of
8Continue to stir! The bubbles come slower and s
l o w e r
- . . .and even s l o w e - r
9Finally one bubble doesnt make it out! The
liquid runs back up the tube!Did you see it ???
- Look at your thermometer!
- THIS IS THE BOILING POINT!!
10This segment is taking boiling points by the
semi-micro method
- A milliliter or two of sample will be used in
this method.
11Start with a good ring stand.Tighten the rod!!
- Add an iron ring about 6 7 inches up from the
base.
12You need a wire gauze with a ceramic center.
- There should be a pencil-size hole in the
- ceramic center.
13Position the wire gauze on the iron ring.
14Clamp a medium-size test tube on the hole -- no
air space!
- Add a milliliter or two of the sample . . .
- and one boiling stone.
15Clamp the thermometer assembly . . .
- . . . with its bulb centered an inch or two above
the liquid sample.
16Light the burner and adjust it to a small flame .
- Play a small flame directly onto the hole in the
wire gauze.
17Bring the sample to a gentle boil.
- Watch for steady drops falling off the
thermometer bulb.
18When the temperature becomes stable . . . no
longer rising . . .
- Record the boiling point!
19bp-rept.doc LABORATORY REPORT FORM DETERMINATION
OF BOILING POINTS NAME
Section Date__________________
_____
Record your comments regarding which of the two
methods gave you the better results. (You will
be using one or both methods when
you are trying to identify your unknowns.)
- Your Laboratory Report Form is due the day on
which you perform the Boiling Points Experiment.
Be prepared to turn it in.