Calorimetry

Not to be confused with Colorimetry.
The world's first ice-calorimeter, used in the winter of 1782–83, by Antoine Lavoisier and Pierre-Simon Laplace, to determine the heat involved in various chemical changes; calculations which were based on Joseph Black’s prior discovery of latent heat. These experiments mark the foundation of thermochemistry.
Snellen direct calorimetry chamber, University of Ottawa[1]
Indirect calorimetry metabolic cart measuring oxygen uptake and CO2 production of a spontaneously breathing subject (dilution method with canopy hood).

In chemistry and thermodynamics, calorimetry (from Latin calor 'heat' and Greek μέτρον (metron) 'measure') is the science or act of measuring changes in state variables of a body for the purpose of deriving the heat transfer associated with changes of its state due, for example, to chemical reactions, physical changes, or phase transitions under specified constraints. Calorimetry is performed with a calorimeter. Scottish physician and scientist Joseph Black, who was the first to recognize the distinction between heat and temperature, is said to be the founder of the science of calorimetry.[2]

Indirect calorimetry calculates heat that living organisms produce by measuring either their production of carbon dioxide and nitrogen waste (frequently ammonia in aquatic organisms, or urea in terrestrial ones), or from their consumption of oxygen. Lavoisier noted in 1780 that heat production can be predicted from oxygen consumption this way, using multiple regression. The dynamic energy budget theory explains why this procedure is correct. Heat generated by living organisms may also be measured by direct calorimetry, in which the entire organism is placed inside the calorimeter for the measurement.

A widely used modern instrument is the differential scanning calorimeter, a device which allows thermal data to be obtained on small amounts of material. It involves heating the sample at a controlled rate and recording the heat flow either into or from the specimen.

  1. ^ Reardon FD, Leppik KE, Wegmann R, Webb P, Ducharme MB, Kenny GP (August 2006). "The Snellen human calorimeter revisited, re-engineered and upgraded: design and performance characteristics". Med Biol Eng Comput. 44 (8): 721–8. doi:10.1007/s11517-006-0086-5. PMID 16937214.
  2. ^ Laidler, K.J. (1993). The World of Physical Chemistry. Oxford University Press. ISBN 0-19-855919-4. OCLC 27034547.