MYP-10: Laboratory work

Experiment: Determination of Boiling Point of a Volatile liquid

Safety features:

The chemicals used in this experiment are flammable and hazardous by inhalation.
Suitable safety precautions must be taken - safety glasses and care.


1. Make a test tube assembly by using the following directions and illustration.

Place about 5 cm3 of the unknown liquid in the boiling tube.

Using a small rubber ring, attach an inverted closed end capillary tube* to the thermometer. The end of the open end capillary should be level with the thermometer bulb.

Insert into the boiling tube and support the thermometer with a clamp so that it does not touch the bottom of the boiling tube.

Assemble a water bath using a 250cm3 or 400cm3 beaker with tap water.

Place the above boiling tube assembly in the water bath so that the surface level of the liquid in the boiling tube is beneath the surface level of the water bath.

Carefully heat the water bath with the Bunsen burner until a rapid stream of bubbles continuously emerges from the capillary tube. Allow to bubble for 1 minute.

Remove the heat source and begin observing the stream of bubbles. When the last bubble emerges from the capillary tube, record the temperature.

Repeat the heating and cooling process several times. Record the temperature reading after each trial, and once you obtain a steady reading use this as the final b.p..

Use the data sheet to decide on the identity of your unknown liquid. How close did you get to the literature value. Calculate your error.

*the closed end capillary tube can be made by carefully heating the very end in the Bunsen flame, rotating throughout until the end melts and closes. Allow it to cool before continuing.