reddit chemical engineering thermodynamics pdf

The Third Law of Thermodynamics states that a perfect crystal at zero Kelvin (absolute zero) has zero entropy.

In one sense you can view the Second Law of Thermodynamics as being the most important of the three in the sense that it is the one most commonly tested upon in this chapter and students should recognize it in any of the three forms presented above. But if ΔS reaction for a spontaneous reaction is negative, then the Second Law does mean that ΔS surroundings must be positive and of greater magnitude in this example so that ΔS system + ΔS surroundings > 0.

To be clear the Second Law does NOT mean that ΔS reaction must be positive as ΔS reaction is just the ΔS system which can be either positive or negative. In chemistry the system is often a chemical reaction under investigation. The last statement of the Second Law of Thermodynamics divides the universe into two parts: the system (what you're investigating) and the surroundings (everything in the universe besides the system). Entropy is covered in much greater detail in the next lesson ( 18.2 Entropy) but that it correlates with disorder will suffice for now. Ultimately, for any spontaneous process the entropy, which is related to randomness or disorder, of the universe increases. The Second Law of Thermodynamics can be stated in any of three synonymous ways:įor a spontaneous process, the entropy of the universe increases.įor a spontaneous process, ΔS universe > 0.įor a spontaneous process, ΔS system + ΔS surroundings > 0

Reddit chemical engineering thermodynamics pdf