Demonstrations in Cryogenics Kenneth A. Lothrop M a r s h f i ~ l rHlrh i School
At very low temperatures many strange and fascinating changes occur in matter. Many of these changes can be used to demonstrate parts of the gas laws and parts of the particle model of matter. These demonstrations can be used not only as a pedagogical tool but also to generate interest in
Before working with liquid nitrogen one should be a w a of the properties shown in the table below. Boiling point Melting point Molar volume-solid liquid In the gas phase, nitrogen is both colorless and odorless. I the liquid phase, it is colorless and has low viscosity.
Interest in cryogenics is growing because of its applications in medicine, industry, and research. Among its applications are superconductivity, cryosurgery, cryogenic burial, and cooling of electronic components or chemical experiments. The most common cryogenic liquids are oxygen, nitrogen, air, helium, and hydrogen. Liquid hydrogen and oxygen are not nenerallv used for crvoeenic demonstrations because of . their extreme reactivity. Crvoaenic materials are available in laree. metro~olitan area;a
