Chemical queries. Especially for introductory chemistry teachers

Auburn, Alabama. J G. MALIK. San Diego State College. San Diego, Californio chemical queries . . . especially for introductory chemistry teachers. Que...
0 downloads 0 Views 1MB Size
chemical queries

J. A. YOUNG Auburn Unirenity Auburn, Alobamo

J G. MALIK , '-

t

. . . especially for

S m Diego Slote College

Son Diego, Colifornie

\

Question Whht is the significance of negative absolnte temperature; how can anything be colder than ODK?

Answer

A short answer is paradoxical. The conventional definition of temperature implies that heat flows spontaneously from a hot,ter object to a cooler one. Heat will flow spontaneously from an object a t - m 'I< to an object a t m OK; hence negative absolute (Kelvin) temperatures are hotter than positive temperatures. Let us try this again, to see what the concept of temperature signifies. Consider a hot, glowing object, such as a metal wire inserted into the flame of a bunsen burner. It glows because excited electrons (excited by energy received from the combustion of the gas in the flame) fall back to lower levels, emitting photons. At all times, the number of excited electrons is much smaller than the number of electrons in lower energy levels. The glowing wire is a t a temperature of approximately +1000"1