Thermodynamics is an integral part of both school physics and chemistry. It is asked a lot in competitive exams like the Joint Entrance Examination (JEE), or other university entrance exams. Students usually study thermodynamics in physics in class 12, while they do so in chemistry in class 11 itself. So, what is thermodynamics exactly, and why do we study it twice over the course of our schooling?
Thermodynamics: what is it?
According to a formal definition, thermodynamics deals with the relation between heat and other forms of energy, such as mechanical, chemical, or electric. It also covers the relationships between all forms of energies, hence why energy laws are studied widely under the broader term of thermodynamics. In fact, thermodynamics is so crucial that some students study it during their first year of engineering as well.
The laws of thermodynamics consist of four well-formulated laws, each concerning a specific scientific phenomenon. For instance, the zeroth law of thermodynamics helps us establish a temperature scale. The first law governs the conservation of energy, while the second law talks about the entropy of a system. The third and final law allows us to establish a scale of entropy, considering the entropy of a perfect crystal of an element in its most stable form to tend to zero.
What does thermodynamics in chemistry contain?
Chemical thermodynamics talks about the relations of heat with other forms of energy within the confines of chemical reactions. The reactions are studied for different numerical values and are also classified as being spontaneous or not. The concept of Gibbs free energy plays a big role in chemical thermodynamics and is a crucial topic when it comes to competitive examinations.
Work, as defined chemically, is usually related to expansion. Since expansion means a change in volume, chemical work is defined as the change in volume times the pressure of the given system. Hence, we can compute the work done during a reaction, or the work needed to be done in order to carry out a reaction.
Thermodynamics in physics
Thermodynamics in physics follows the same basic principles, studying how thermal energy is converted into other different forms of energy. Here, heat, temperature, specific heat, and latent heat are concepts which are studied. Newton’s law of cooling is another important topic studied under the thermodynamics of physics. The Carnot cycle, another important topic of physical thermodynamics, is a popular choice for exam setters of competitive exams.
Where’s the difference, then?
Fundamentally, thermodynamics in physics and chemistry is the same. The only difference is the notation of work in both, with work done by the system taken as positive in physics, and work done on the system taken as positive in chemistry. The reason for this distinction can be that in physics, we are concerned with the study of the system and what it can do for us, whereas in chemistry, we are concerned with what we can do on the system to affect some kind of change in it.
So, this is the distinction between the thermodynamics of physics and chemistry! Hope it is all clear in your mind now!
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