Assignment no 2 Subject Name: Physical Chemistry Subject Code: CHE201 Dated: 27 Nov 2023
Student Name: abc Student I’D: xyz QUESTION: What do you know About Enthalpy and Entropy? How are these related to each other? Describe in details. ANSWER: Enthalpy: Enthalpy (H) is a thermodynamic property that represents the total heat energy in a system. It takes into account both the internal energy of the system and the energy required to create or maintain its structure. Enthalpy is often used to describe the heat flow in chemical reactions or phase changes. For example, when a chemical reaction takes place, the enthalpy change can tell us whether heat is released or absorbed during the reaction. Entropy: Entropy (S), on the other hand, is a measure of the system's disorder or randomness. It quantifies the number of ways in which the particles or molecules in a system can be arranged. A highly ordered system has low entropy, while a more disordered system has high entropy. Entropy is a fundamental concept in understanding the direction of natural processes. According to the second law of thermodynamics, the total entropy of an isolated system always tends to increase over time. Relationship between Enthalpy and Entropy with Example: EXAMPLE: Suppose there is a cup of hot coffee. The Enthalpy of the coffee represents the entire heat energy contain in the cup. As the coffee cools down, the enthalpy decreases. Now, let’s think about the Entropy. At first, when the coffee is hot, the molecules are moving speedily and arbitrarily, resultant in high entropy. As the coffee cools down, the molecules slow down and become more ordered, leading to a decrease in entropy.  So, in this example, as the enthalpy decreases (heat energy decreases), the entropy also decreases (randomness decreases). Relationship between Enthalpy and Entropy: Now, let's talk about the relationship between enthalpy and entropy.  The second law of thermodynamics states that the total entropy of an isolated system always increases or remains constant in a spontaneous process.  This means that natural processes tend to move towards a state of higher entropy.  However, the change in enthalpy also plays a role in determining whether a process is spontaneous or non-spontaneous. The change in free energy (ΔG) is a measure of the spontaneity of a process. It is related to the change in enthalpy (ΔH) and entropy (ΔS) through the equation: ΔG = ΔH - TΔS  Where, T represents the temperature.  If the ΔG value is negative, the process is spontaneous and favors the formation of products.  If the ΔG value is positive, the process is non-spontaneous and requires an input of energy to proceed. So, to summarize, enthalpy and entropy are related through the second law of thermodynamics. Enthalpy represents the total heat energy in a system, while entropy represents the system's disorder or randomness. Their interplay, along with temperature, determines the spontaneity of a process. //////////////////////ASSIGNMENT COMPLETED//////////////////////