How to Find a Boiling Point Substance

If you are looking for high-quality products, please feel free to contact us and send an inquiry, email:

A liquid’s boiling point is the temperature at which its vapor pressure equals atmospheric pressure and it changes into a gas. When heated, molecules at the surface of a liquid atomize and move rapidly throughout the liquid to form bubbles of vaporized liquid (gas). The normal boiling point is a critical temperature for storing chemicals, as containers of liquids with a low boiling point could potentially produce so much vapor that they would explode.

The normal boiling point of a compound is directly related to its molecular structure and polarity. Compounds with covalent bonds that are long and large tend to have lower normal boiling points than compounds with shorter and smaller bonds. Likewise, compounds that form hydrogen bonds have higher normal boiling points than those that do not. The shape of a molecule also influences its normal boiling point, with more compact molecules having lower boiling points than those that are longer and more spread out.

To find a substance’s boiling point, set up the contraption shown on page 46 of your book. Clamp a test tube with your mystery fluid above a heat-spreading screen. Light a burner, and read the thermometer every 30 seconds. Continue until the liquid begins to boil, then record your results on a graph of temperature versus time. Hand your graph to me when complete.