How does the entropy of the surroundings change during an exothermic reaction? An endothermic re

How does the entropy of the surroundings change during an...

Key Concepts

Entropy

Entropy is a thermodynamic quantity that measures the degree of randomness or disorder in a system. It is a fundamental concept in understanding the direction of physical and chemical processes, as systems naturally progress toward states with higher total entropy.

Heat Transfer and Surroundings

Heat transfer between a system and its surroundings is central to thermodynamics. When a reaction occurs, energy is exchanged via heat, which directly affects the entropy of the surroundings, making it a key aspect in predicting the direction and spontaneity of reactions.

Exothermic Reaction

An exothermic reaction releases heat into its surroundings. This heat release increases the thermal motion of the particles in the surroundings, leading to an increase in their entropy. The overall system, taking both the reaction and the surroundings into account, is evaluated for spontaneous change using the total entropy change.

Endothermic Reaction

An endothermic reaction absorbs heat from its surroundings. Generally, this absorption means the surroundings lose heat, which could decrease their entropy. However, the reaction may still be spontaneous if the increase in entropy within the system outweighs the loss in the surroundings, leading to an overall increase in total entropy.

Spontaneous Process

A spontaneous process is one that occurs without the need for external intervention. While the energy exchange (exothermic or endothermic) is important, spontaneity is ultimately determined by the total entropy change of the universe (system plus surroundings) or, equivalently, by the Gibbs free energy change under constant temperature and pressure conditions. Even an endothermic process can be spontaneous if the entropy increase of the system or the environment is sufficiently large.

Transcript

00:01 Chapter 20, problem 6, is about the entropy of the surroundings during the exothermic reaction, as well as the surroundings during an endothermic reaction.

00:11 So to review this, let's look at the second law of thermodynamics.

00:17 This law states that the entropy of the universe is going to be positive in a spontaneous reaction or a spontaneous change.

00:28 And the entropy of the universe is actually equal to the entropy of the system, plus the entropy of the surroundings.

00:41 So this is entropy of the universe.

00:44 This is the entropy of the surroundings plus the entropy of your system.

00:54 So i have two boxes here.

00:57 One is representing one universe where there's an exothermic change, and here is a universe where there's an endothermic change.

01:05 Let's first think about the exothermic.

01:07 In an exothermic change, heat is released.

01:13 So in this center area, we have our system that where the reaction is occurring and this black box is representing our surroundings.

01:22 Same here.

01:23 We have our system and the black box is our surroundings.

01:26 In an exothermic reaction, heat is released from the system into the surroundings.

01:33 Let's try that again.

01:38 So heat is being released into the surroundings and an exothermic reaction.

01:43 That means the degree of freedom, the freedom of the particle.

01:46 Motion in your surroundings is going to increase.

01:52 So in an exothermic reaction, the entropy of your surroundings increases.

01:57 Let's think about an endothermic reaction.

02:00 Endothermic reaction requires energy to occur.

02:03 So that means heat is being absorbed into the system from the surroundings.

02:11 And therefore, heat is lost...

Please give Ace some feedback