Boiling Point Determination
Introduction: To learn how to investigate the physical property of boiling point. To carry out
experiments using a “micro” technique and calibration curve.
Chemical Responsibility: The unknown chemicals have hazards associated with them: methanol,
isopropyl alcohol, and ethanol are flammable liquids and are toxic by ingestion. Wear goggles to
protect your eyes from the chemicals, and avoid touching broken glass. Be careful while putting
the rubber stopper on the thermometer, for it can break. Throw all broken glass in the broken
glass box, and discard the unknown liquid from the small test tube into the bottle labeled
WASTE EXPERIMENT BOILING POINT UNKNOWNS.
Report sheet and sample calculations: see attached sheet and graph
Results: The boiling point was determined through the assembly of a thermometer attached to a
small test tube with rubber bands. Inside the test tube was a capillary tube submerged with an
unknown liquid. This liquid/thermometer apparatus was placed in a beaker filled with water.
This was placed over a Bunsen burner to allow the water to boil. When bubbles rose steadily
from the capillary then the heat was removed and the tube was observed until the bubbles
terminated. When this occurs, the temperature must be read on the thermometer. When this
occurred it means the boiling point of the unknown has been found, which is when the pressure
vapor inside the small capillary tube is equal to the atmospheric pressure. This procedure was
repeated twice to attain a measurable boiling point and to test