The specific heat of water is approximately 1 kcal/kg ºC, while its volumetric heat capacity is 1000 kcal/m³ ºC.
Heat capacity is an expression that identifies the result of dividing the heat transfer that, regardless of the process that takes place, reaches a system or body and the variation in temperature experienced by it.
Expressed another way, also known as thermal capacity , it refers to the energy required to cause, in a certain substance, the thermal increase in a unit of temperature . This type of thermal inertia parameter indicates a lesser or greater difficulty for a body when it comes to undergoing changes in its temperature from the supply of heat .
As can be seen from the theory , pressure and temperature have an influence on the heat capacity , which is considered an exclusive extensive property of each system or body in particular. It is important to distinguish very well between it and the specific thermal capacity (or specific heat ) because in this case it is an intensive property alluding to the capacity that a body has with respect to heat storage, being the quotient of the division between the aforementioned heat capacity and the mass of the element worked.
Types of heat capacity
It is possible to recognize several types of heat capacity . In addition to the specific heat capacity indicated above (framework in which we differentiate between mass specific heat , molar specific heat , specific heat of substances and specific heat of gases ), the category of volumetric heat capacity becomes relevant.
In the latter case, the focus is on how much energy in the form of heat must be supplied to a unit volume of a certain material to stimulate a rise of one unit in its temperature . By establishing the volumetric heat capacity, it is revealed how much thermal energy a substance can accumulate, once its temperature varies but not its phase, according to its volume.
It should be noted that when working with gases it is essential to make the distinction between specific heat at constant volume and specific heat at constant pressure .
Experimental methods
When searching for information about experimental methods that are related in some way to heat capacity, several alternatives come to light to take into account. Among them, the benefits of calorimetry , which is very useful for thermodynamics (because it provides data regarding the heat emitted or absorbed within the isothermal segment corresponding to a Carnot cycle ).
This is a measurement of the specific heat of a body made with an instrument called a calorimeter .
There are calculations that allow us to establish the specific heat of the various nucleated elements in the periodic table.
There are indirect calorimetry (focused on calculating the amount of heat produced by living organisms) and direct calorimetry (aimed at measuring the energy released in the oxidation process of matter). When it is carried out while conserving the volume , it is defined as constant volume calorimetry : if you want to find out the heat capacity of a sample of fuel, both liquid and solid, whose volume remains constant, a device called a pump is used. calorimetric . Since no work (physics) arises from this type of calorimetry , it was concluded that the heat of a system being measured is equal to the change observed in its internal energy . The researchers maintain that, at constant volume , heat capacity does not depend on temperature . It has also been determined that the pressure is not invariable: therefore, if a difference arises between the initial and final state, an adjustment is required with respect to the measured heat in order to facilitate the change in enthalpy .
It is constructive to learn, even, about the measurement of polyatomic gases and their molar heat capacity . In this context, it is observed that there is a moderate increase in the molar heat capacity as the temperature rises. For a precise approach, therefore, it is advisable to appeal to quantum statistical mechanics .
Thanks to the thermal inertia of the ocean, global warming has been delayed, to a certain extent, over several years.
Examples of heat capacity
Having examples of the application of heat capacity can contribute to a better understanding of the importance of this notion. It is interesting to know, to detail a specific case, that water has a very high specific heat capacity . This is why it must, per unit of mass, absorb a large amount of heat for its temperature to rise. It has also been indicated that the heat capacity of the aqueous content of a pool is greater compared to that of a bottle with half a liter of water inside.
Other investigations have allowed us to deduce that the increase in the mass of a certain substance is accompanied by an increase in its heat capacity as a result of the increase in thermal inertia . This panorama makes it difficult for the temperature of said substance to vary. It is attractive, at this point, to dwell on the theoretical definition of thermal inertia and how it translates into practice. Multiple phenomena or manifestations that are associated with climate change reflect consequences of the aforementioned thermal inertia (that of the ocean, specifically, by serving as a climate regulator, it has managed to delay the effects of global warming for a long period of time).