 J. D. Kemp

J. D. Kemp is a chemist credited with K. S. Pitzer on the 1937 paper The Entropy of Ethane and the Third Law of Thermodynamics. Hindered Rotation of Methyl Groups by J. D. Kemp and Kenneth S. Pitzer. The paper connects molecular internal rotation with entropy and the third law of thermodynamics; the originating record identifies Kemp by initials.^[ref]

The physical question is whether rotation around a carbon-carbon bond can be treated as free or whether angle-dependent potential energy must be included. For example, a model $V(\theta )=0$ assigns the same energy to every orientation; a threefold model $V(\theta )=B(1+\cos 3\theta )/2$ distinguishes staggered conformations from eclipsed conformations. Such models predict different populations of orientations and therefore different contributions to entropy. The example explains the thermodynamic relevance of the paper's question; it is not a reconstructed numerical result from the 1937 experiment.

Kemp's verified contribution here is coauthorship of that focused physical-chemistry study. The bibliographic evidence does not assign a separate apparatus design or calculation to each coauthor, and it does not establish a full name or a portrait.