At absolute zero, only one quantum state would represent the system, so the entropy is zero. As heat flows in, the multiplicity increases. Because entropy increases with the logarithm of the temperature, the rate of change (ΔS/ΔT) is proportional to 1/T. The molar entropy of water at zero Celsius equals the molar entropy of zero Celsius ice plus the heat of fusion divided by 273 Kelvin. That's what ΔS/ΔT tells us. The entropy of a gas can be calculated theoretically as a state function, depending on Temperature, Volume, and MW (or T, P and MW) or it can be determined experimentally by the addition of heat from temperatures close to 0 K through melting, vaporization to the final temperature.

The residual entropy of nitrous oxide at 0K is an interesting problem. Because the molecules in the crystal can be oriented in one of two ways, there is still entropy at absolute zero because of the random alignment of nitrous oxide molecules in the perfectly motionless lattice.

The WikiPremed MCAT Course is a comprehensive course in the undergraduate level general sciences. Undergraduate level physics, chemistry, organic chemistry and biology are presented by this course as a unified whole within a spiraling curriculum. Please read our policies on Privacy and Shipping & Returns.  Contact Us. MCAT is a registered trademark of the Association of American Medical Colleges, which does not endorse the WikiPremed Course. WikiPremed offers the customers of our publications or our teaching services no guarantees regarding eventual performance on the MCAT.

Creative Commons License
WikiPremed is a trademark of Wisebridge Learning Systems LLC. The work of WikiPremed is published under a Creative Commons Attribution NonCommercial ShareAlike License. There are elements of work here, such as a subset of the images in the archive from WikiPedia, that originated as GNU General Public License works, so take care to follow the unique stipulations of that license in printed reproductions.