Specific heat is the heat required by a substance per unit mass to increase its temperature by one degree Celsius.
Specific heat is a concept that is used in the field of physics with reference to the heat that a substance requires per unit of mass to increase its temperature by one degree Celsius .
To understand the notion, therefore, we must have several ideas clear. Heat is called, in the context of physics, the energy that moves from one body to another, causing changes of state and dilation. Mass , on the other hand, is a physical quantity that refers to the amount of matter that is present in a body. Temperature , finally, is another physical quantity, in this case oriented to the level of heat that the environment or a body has.
If we take these concepts and link them to the definition that we mentioned in the first paragraph, we can see that specific heat is the energy needed by a unit of mass of a substance to increase its heat by one degree Celsius .
Specific heat characteristics
Specific heat, which can be represented by a lowercase letter C ( c ), is usually linked to the initial temperature of the substance. This is an intensive property of matter : it is not related to its quantity or size.
As the specific heat of a substance increases, a greater amount of heat is needed to achieve the increase in temperature . If we take the case of substances in a gaseous state, we can notice that nitrogen has a mass specific heat higher than that of oxygen . Therefore, more energy is needed to achieve the increase of heat in a unit mass of nitrogen than oxygen.
The concept of specific heat emerged in the 18th century.
Origin of the concept
The origin of the name of this concept is found in the research of the Scottish physicist Joseph Black , who carried out various calorimetric experiments and coined the phrase "heat capacity " . Calorimetry, for its part, is the branch of physics that aims to measure heat in a change of state or a chemical reaction using an instrument known as a calorimeter .
It is important to keep in mind that Black was born in 1728 and died a year before the beginning of the 19th century , so the vision that science had of these and other phenomena was very different from the current one. For example, thermodynamics and mechanics were taken as independent sciences, and this leads us to think that the concept of specific heat, conceived at that time, is not entirely coherent with current ideas of science; However, since it has taken root in the community, they continue to use it without modifying it.
Calculation of specific heat
With respect to the equations that we must use to calculate the specific heat value, we can say that the average specific heat capacity (which is represented with the symbol ĉ ) corresponds to a temperature range defined as follows: ĉ = Q / mΔT .
The variable Q represents the energy that is transferred between two systems or between one and its environment, in the form of heat. m , for its part, corresponds to the mass of the system (if we were treating the molar specific heat, then we should use the letter n ). Finally, there is the temperature delta ( ΔT ), that is, the increase in temperature that the system goes through. We must not forget that the two variables found after the division sign must be multiplied together ( m times ΔT ).
In engineering, the measurement of specific heat usually has mass as the quantity of substance, both in kilograms and grams. In chemistry, on the other hand, it is convenient to use the unit mole.