The Laws Of Thermodynamics Explained

The zeroth law of thermodynamics states that if two systems are both in thermal equilibrium with a third system, then they are in thermal equilibrium with each other. This law allows for definition of the empirical temperature as a system property (Boundless, undated). Hence, if system 1 has the same temperature as system 2 and system 2 has the same temperature as system 3, then the temperature of system 1 is the same as that of system 3. Three systems that are in thermal equilibrium have the same temperature, with the law allowing for definition of empirical temperature.

The first law of thermodynamics states that energy cannot be createdor destroyed; it can only be changed from one form to another form or transferred. For example, kinetic energy in wind changes to mechanical energy and then to electrical energy. This first law of thermodynamics is also known as the law of conservation of energy(Cengel and Boles 2014).

The second law of thermodynamics states that an isolated system’s entropy always increases. This is because isolated systems, systems that neither matter nor energy can pass through because of the enclosing boundaries,naturally evolve towards thermal equilibrium. By achieving thermal equilibrium, the system achieves maximum entropy. Notably, isolated system is hypothetical for calculations only, since they do not really exist (Cengel and Boles 2014). However, the universe is defined as an isolated system, with its entropy always increasing.

The third law of thermodynamics states that as a system’s temperature approaches absolute zero, the system’s entropy approaches a constant value. This means that there is typically no entropy in a system with 0 K temperatures, though residual entropy based on the ground state of the system may exist (Boundless, undated).