# Kopp's law

Hermann Franz Moritz Kopp

Kopp's law can refer to either of two relationships discovered by the German chemist Hermann Franz Moritz Kopp (1817–1892).

1. Kopp found "that the molecular heat capacity of a solid compound is the sum of the atomic heat capacities of the elements composing it; the elements having atomic heat capacities lower than those required by the Dulong–Petit law retain these lower values in their compounds."[1]
2. In studying organic compounds, Kopp found a regular relationship between boiling points and the number of CH2 groups present.[2]

## Kopp–Neumann law

The Kopp–Neumann law, named for Kopp and Franz Ernst Neumann, is a common approach for determining the specific heat C (in J·kg−1·K−1) of compounds using the following equation:[3]

${\displaystyle C=\sum _{i=1}^{N}C_{i}f_{i}}$ ,

where N is the total number of compound constituents, and Ci and fi denote the specific heat and mass fraction of the i-th constituent. This law works surprisingly well at room-temperature conditions, but poorly at elevated temperatures.[3]

## References

• Frederick Seitz, The Modern Theory of Solids, McGraw-Hill, New York, USA, 1940, ASIN: B000OLCK08
1. ^ See page 96 of Millard, Earl Bowman (1921). Physical Chemistry for Colleges. New York: McGraw-Hill. p. 96. Kopp's Law.
2. ^ See page 942 of Miller, William Allen (1869). Elements of Chemistry. London: Longmans, Green, Reader, and Dyer.
3. ^ a b Kauwe, Steven K.; Graser, Jake; Vazquez, Antonio; Sparks, Taylor D. (2018-05-29). "Machine Learning Prediction of Heat Capacity for Solid Inorganics". Integrating Materials and Manufacturing Innovation. 7 (2): 43–51. doi:10.1007/s40192-018-0108-9. ISSN 2193-9764. S2CID 65239690.