The thermal expansion of hydrogen and ethylene
Housley, Robert Melvin
Rorschach, Harold E., Jr.
Master of Arts
A direct measurement of the thermal expansion of solid hydrogen Is of Interest (1) to compare with previously reported density values measured at different temperatures, and (2) to compare with a computation of the thermal expansion made using other thermodynamic information. An apparatus has been constructed to make this measurement. It is basically a parallel plate capacitor mounted in such a way that any thermal expansion of the hydrogen gives a greatly magnified change in capacitance. Results so far, though not conclusive, indicate that hydrogen has a much smaller coefficient of expansion than was expected, infinity being < 10 to the -5 per degrees kelvin. With the same apparatus, the thermal expansion of ethylene in the range from 64 to 73°K was measured, giving the result infinity av = 2.5 x 10 to the -4 per °K.