Calorimetry



 

Calorimetry is the science of measuring the temperature, is said to be the founder of calorimetry.[1]

Indirect calorimetry calculates 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. Of course, 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.

Constant-volume

Constant-volume calorimetry is calorimetry performed at a constant volume. This involves the use of a constant-volume calorimeter.

No work is performed in constant-volume calorimetry, so the heat measured equals the change in internal energy of the system. The equation for constant-volume calorimetry is (the heat capacity at constant volume is assumed to be constant):

q = C_V \Delta T = \Delta U \,

where

ΔU is change in internal energy,
ΔT is change in temperature and
CV is the heat capacity at constant volume.

Since in constant-volume calorimetry the enthalpy ch

Constant-pressure

Constant-pressure calorimetry is calorimetry performed at a constant pressure. This involves the use of a constant-pressure calorimeter.

The heat measured equals the change in internal energy of the system minus the work performed:

q = \Delta U - w \,

Since in constant-pressure calorimetry, enthalpy change:

q = \Delta H = H_\mathrm{final} - H_\mathrm{initial} \,

This formula is a simplified representative of Hess's Law.

See also

References

  1. ^ Laider, Keith, J. (1993). The World of Physical Chemistry. Oxford University Press. ISBN 0-19-855919-4. 



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