Thermochemistry studies the absorption and release of heat
Thermochemistry is the area of thermodynamics that is dedicated to the study of energy exchanges produced within the framework of a chemical reaction . Before delving into the idea of thermochemistry, therefore, we must pay attention to the notion of thermodynamics.
Relationship with thermodynamics
Thermodynamics is the sector of physics that analyzes the links between heat and the rest of the forms of energy . Regarding heat , we can affirm that it is the energy that moves between bodies, causing changes of state and their dilation.
Returning to thermochemistry, it can be said that it involves the application of thermodynamics to physics. This discipline examines processes in which heat is absorbed (known as endothermic ) and those in which heat is released ( exothermic processes).
Energy exchanges are usually expressed in the magnitude called enthalpy , which is the sum of the internal energy of a body plus the product of the external pressure times its volume. Chemical reactions are generally considered to take place at constant volume or constant pressure.
chemical reactions
Returning to previous concepts, chemical reactions with a negative variation in enthalpy are exothermic reactions (during the reaction, heat is lost to the system ). On the contrary, if the variation is positive in terms of enthalpy, these are endothermic reactions (the system absorbs heat within the framework of the reaction).
It is important to note that, while the chemical reaction develops, there are several magnitudes that can register changes. Among them we can mention volume , pressure, temperature and concentration.
State functions
Above we talked about the state variable called enthalpy , one of those that can appear in a system in equilibrium in the field of thermodynamics. Among the rest we find the following: internal energy, temperature, pressure, volume, density, entropy, Gibbs free energy and polarization .
All of this is framed in the concept of state function , a macroscopic magnitude that allows us to characterize the state of systems in equilibrium and that is not linked to the way in which they have reached such a state. Given any thermodynamic system that is in equilibrium, it is possible to choose some state variables, provided that through their values we can identify its state without exception .
It should be noted that the value of these functions is only linked to the thermodynamic state of the moment in which it is measured , independently of the way in which it was reached. In other words, if at a point in time we analyze two systems in equilibrium and obtain an equivalence, this does not mean that the same thing had happened some time ago or that it will happen again.
Applications of thermochemistry
It is important to note that thermochemistry has many uses, and for this reason we can find it in various disciplines . The field of industry is where it is most frequently applied; There, its usefulness is the explanation of laboratory phenomena, as well as those of a biological nature.
Its application stands out in the study of laboratory phenomena
For example, we can talk about its intervention when we try to find out the amount of energy that certain living beings consume through chemical formulas designed to describe reactions that are specific to them.
We could also mention the research that aims to discover the magnitude of heat energy that is released after subjecting a thermogel to a chemical reaction, which occurs due to supersaturation. A thermogel is a material that has a gel that allows it to cancel the absorption of heat produced by the human body, so that it maintains its own temperature and can act as a thermal regulator.