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Heat capacity or thermal capacity is a physical property of matter, ... constant-volume and constant-pressure heat capacities, rigorously defined as partial ...
In thermodynamics, the heat capacity at constant volume, , and the heat capacity at constant pressure, , are extensive properties that have the magnitude of energy divided by temperature. Relations [ edit ]
The left-hand side is the specific heat capacity at constant volume of the material. For the heat capacity at constant pressure, it is useful to define the specific enthalpy of the system as the sum (,,) = (,,) +. An infinitesimal change in the specific enthalpy will then be
Table of specific heat capacities at 25 °C (298 K) unless otherwise noted. [citation needed] Notable minima and maxima are shown in maroon. Substance Phase Isobaric mass heat capacity c P J⋅g −1 ⋅K −1 Molar heat capacity, C P,m and C V,m J⋅mol −1 ⋅K −1 Isobaric volumetric heat capacity C P,v J⋅cm −3 ⋅K −1 Isochoric ...
In the first, constant-volume case (locked piston), there is no external motion, and thus no mechanical work is done on the atmosphere; C V is used. In the second case, additional work is done as the volume changes, so the amount of heat required to raise the gas temperature (the specific heat capacity) is higher for this constant-pressure case.
Specific heat capacity ... if x is the volume, then X is the pressure. ... If we change the temperature T by dT while keeping the volume of the system constant, ...
Replacing work with a change in volume gives = Since the process is isochoric, dV = 0, the previous equation now gives = Using the definition of specific heat capacity at constant volume, c v = (dQ/dT)/m, where m is the mass of the gas, we get =
In the 19th century, German chemist and physicist Julius von Mayer derived a relation between the molar heat capacity at constant pressure and the molar heat capacity at constant volume for an ideal gas.