Joule Expansion - Real-gas Effect

Real-gas Effect

Joule performed his experiment with air at room temperature which was expanded from a pressure of about 22 bar. Air, under these conditions, is almost an ideal gas, but not quite. As a result the real temperature change will not be exactly zero. With our present knowledge of the thermodynamic properties of air we can calculate that the temperature of the air should drop by about 3 degrees Celsius when the volume is doubled under adiabatic conditions. However, due to the low heat capacity of the air and the high heat capacity of the strong copper containers and the water of the calorimeter, the observed temperature drop is much lower, so Joule found that the temperature change was zero within his measuring accuracy.

Read more about this topic:  Joule Expansion

Famous quotes containing the word effect:

    To see distinctly the machinery—the wheels and pinions—of any work of Art is, unquestionably, of itself, a pleasure, but one which we are able to enjoy only just in proportion as we do not enjoy the legitimate effect designed by the artist.
    Edgar Allan Poe (1809–1849)