Derived quantities that specify heatcapacity as an intensive property (i.e., independent of the size of a sample) are the molar heatcapacity, which is the heatcapacity per mole of a pure substance, and the specificheatcapacity, often simply called specificheat, which is the heatcapacity per unit mass of a material ([c]=J/(kg*K)).
In such cases, the specificheatcapacity will be a fraction of the maximum.
As the temperature approaches absolute zero, the specificheatcapacity of a system also approaches zero, due to loss of available degrees of freedom.
So, we have: The subscript p is a reminder that the value of specificheatcapacity is valid only if the transformation takes place at constant pressure.
Copper has a specificheatcapacity of 0.383 kilojoules per kilogram per kelvin (0.383 kJ kg-1 K-1).
Heatcapacity is the amount of energy required to change a substance's temperature by a given amount.
To understand the behavior of real gases, we must take the following properties into account: compressibility variable specificheatcapacity van der Waals forces non-equilibrium thermodynamic effects molecular dissociation and elementary reactions with variable composition For most applications, such a detailed analysis is unnecessary, and the ideal gas approximation can be used with reasonable accuracy.
Because the specificheatcapacity of water (4.184 J g–1 K–1) is known to high precision, a measurement of its temperature rise due to the reaction enables one to calculate the quantity of heat released.
The resulting calorimeter constant, expressed in J K–1, is called the heatcapacity of the calorimeter.
For reactions that can be initiated by combining two solutions, the temperature rise of the solution itself can provide an approximate value of the reaction enthalpy if we assume that the heatcapacity of the solution is close to that of pure water, which will be nearly true if the solutions are dilute.
To measure a heatcapacity, a warm sample is placed in the inner compartment, which is surrounded by a mixture of ice and water.
This, combined with the heat of fusion of ice, gives the quantity of heat lost by the sample as it cools to 0°C.
Heat released upon a reaction is equal to the standard enthalpy change if reactants and products are at equal temperature and constant pressure.
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