## Enthalpy vs Entropy

JaylinWangDis1L
Posts: 102
Joined: Wed Sep 30, 2020 10:09 pm

### Enthalpy vs Entropy

This might be a dumb question but I just realized I don't actually know the difference between enthalpy and entropy. Can someone explain it to me :')

Isabelle Hales 1J
Posts: 100
Joined: Wed Sep 30, 2020 9:41 pm
Been upvoted: 1 time

### Re: Enthalpy vs Entropy

Hi! Enthalpy describes the amount of heat released or absorbed at a constant pressure. Entropy, on the other hand, is a measure of the likelihood that the system will be in a particular state. If there are more possible states for the system to be in, the entropy increases. (In high school, I remember hearing that entropy is equivalent to disorder if that is helpful). Also, it is important to keep in mind that enthalpy is a state property while entropy is an extensive property (depends on the number of particles). Hope this helps!

805295074
Posts: 53
Joined: Tue Nov 17, 2020 12:18 am

### Re: Enthalpy vs Entropy

Another helpful idea I learned is that entropy is "the chaos in the universe" and we do work (exerting energy) to put it back in order.

Kayle Lim 2C
Posts: 52
Joined: Wed Feb 19, 2020 12:16 am

### Re: Enthalpy vs Entropy

The straightforward definition of both would be

Enthalpy: the amount of heat gained or released by a system (denoted by H)
Entropy: the amount of disorder or randomness in a system (denoted by S)

Both enthalpy and entropy contribute to the Gibbs free energy equation! Units for enthalpy are usually kilojoules per mole and units for entropy are usually joules per Kelvin.

^^ I found this video to be really helpful to understanding what "chaos" and "randomness" actually mean as the video compares the differences of enthalpy and entropy by describing water in its form of ice and liquid. I hope this helps !

Morgan Gee 3B
Posts: 100
Joined: Wed Sep 30, 2020 9:48 pm

### Re: Enthalpy vs Entropy

Enthalpy is represented by H and is heat. Heat is defined as energy either entering or leaving a system. When an object cools down, that object is losing energy in the form of heat, meaning that enthalpy is negative. Entropy is represented by S and can be called disorder. This has to do with degeneracy and microstates as they can be used to calculate S. Some examples of increasing entropy would be increasing temperature or producing more moles of gas in a chemical reaction.

Ivy Tan 1E
Posts: 100
Joined: Wed Sep 30, 2020 10:09 pm
Been upvoted: 2 times

### Re: Enthalpy vs Entropy

Hi!
Enthalpy (represented by the variable H) is the heat released or absorbed by a system under constant pressure. Entropy (represented by the variable S) is the measure of molecular disorder or randomness in a system. Hope this helps!!

Moura Girgis 1F
Posts: 111
Joined: Wed Sep 30, 2020 10:00 pm

### Re: Enthalpy vs Entropy

A difference between the two is that enthalpy tends to be negative, as there is a change in heat, while entropy tends to be positive, as there is a change in disorder.

Jalaia Jackson 2G
Posts: 110
Joined: Wed Sep 30, 2020 9:45 pm

### Re: Enthalpy vs Entropy

This isn't a dumb question at all. Enthalpy has to deal with heat, while entropy has to do with the state of a system. In more depth, enthalpy is the heat content of a system, and enthalpy changes when energy is either lost or gained. Entropy refers to the level of disorder of a system depending on the state it is in like gas, liquid, and solid.

Astha Sahoo 3I
Posts: 104
Joined: Wed Sep 30, 2020 9:52 pm
Been upvoted: 1 time

### Re: Enthalpy vs Entropy

Enthalphy is the difference in heat, while entropy is the difference in disorder. Usually, spontaneous reactions involve the increase of entropy since the universe wants to always increase entropy.

Chloe Shamtob 2H
Posts: 118
Joined: Wed Sep 30, 2020 9:55 pm

### Re: Enthalpy vs Entropy

Enthalpy, which is denoted by H, is used to describe the amount of heat released or absorbed at a constant pressure. Entropy, which is denoted by S, is used to measure of the likelihood that the system will be in a particular state and the disorder of the particles. The more possible states a system can have the higher the entropy.

Edwin Liang 1I
Posts: 100
Joined: Wed Sep 30, 2020 9:34 pm

### Re: Enthalpy vs Entropy

Entropy is the amount of disorder in a system. Enthalpy is the amount of heat released or absorbed in a given system. Temperature and phase changes affect entropy and enthalpy.

jasmineculilap_3F
Posts: 101
Joined: Wed Sep 30, 2020 9:40 pm

### Re: Enthalpy vs Entropy

Entropy is disorder while enthalpy is heat. Enthalpy is the heat absorbed/released in a system while entropy is the measure of disorder.

Riddhi Mehta 2C
Posts: 53
Joined: Wed Nov 18, 2020 12:21 am

### Re: Enthalpy vs Entropy

Entropy is the measure of disorder or level of chaos in a system whereas enthalpy is the energy in the system.

Sara Sandri 2B
Posts: 60
Joined: Wed Nov 18, 2020 12:18 am

### Re: Enthalpy vs Entropy

Enthalpy is a measure of the heat of a reaction, whether that heat is absorbed (positive enthalpy) or whether that heat is released (negative enthalpy). Entropy is a measure of disorder in a reaction.

DominicMalilay 1F
Posts: 114
Joined: Wed Sep 30, 2020 9:36 pm

### Re: Enthalpy vs Entropy

Enthalpy is also known as heat, while entropy is the chaos or the disorder of molecules.

Michelle Nguyen 3F
Posts: 105
Joined: Wed Sep 30, 2020 10:03 pm

### Re: Enthalpy vs Entropy

Hello! Enthalpy is the measure of total heat present in the thermodynamic system where the pressure is constant. Entropy is the measure of disorder in a thermodynamic system.

Can Yilgor 2D
Posts: 104
Joined: Wed Sep 30, 2020 10:09 pm

### Re: Enthalpy vs Entropy

Here are the definitions of enthalpy and entropy that I have in my notes:

Enthalpy: the amount of heat released or absorbed at constant pressure (state property)
Entropy: the number of accessible states/positions that can be occupied (extensive property)

Liam Bertrand 3
Posts: 101
Joined: Wed Sep 30, 2020 9:53 pm

### Re: Enthalpy vs Entropy

Enthalpy involves heat released, while entropy is the number of states a system can be in.

Kayla Booker 1F
Posts: 100
Joined: Wed Sep 30, 2020 9:43 pm

### Re: Enthalpy vs Entropy

Enthalpy is the change in heat while entropy is the change in chaos, or disorder

Edgar Velazquez 2K
Posts: 50
Joined: Wed Nov 20, 2019 12:20 am

### Re: Enthalpy vs Entropy

Enthalpy is more so the change in heat (loss/gain) of the system while entropy is more like the change in order/disorder of the system.

John_Tran_3J
Posts: 108
Joined: Wed Sep 30, 2020 9:58 pm

### Re: Enthalpy vs Entropy

Enthalpy is referred to the amount of energy released (heat released) and entropy refers to the amount of disorder in the world (refers to the second law of thermodynamics,)

Isabella Cortes 2H
Posts: 100
Joined: Wed Sep 30, 2020 9:37 pm

### Re: Enthalpy vs Entropy

HI! Enthalpy is the amount of the heat that is released and entropy is the amount of disorder in a system.

Cristian Cortes 1L
Posts: 54
Joined: Thu Mar 05, 2020 12:15 am

### Re: Enthalpy vs Entropy

Enthalpy = H = Heat in system , given or taken
Entropy = S = System disorder (change from order to disorder, vise versa)

This has been the simplest form I have put it all quarter. Hope it helps. still gets confusing at times.

Diana Aguilar 3H
Posts: 120
Joined: Wed Sep 30, 2020 9:50 pm

### Re: Enthalpy vs Entropy

Hi! Enthalpy focuses on the change of heat in a system, while entropy focuses on the change in disorder of a system

Posts: 106
Joined: Wed Sep 30, 2020 9:35 pm
Been upvoted: 2 times

### Re: Enthalpy vs Entropy

Enthalpy refers to the transferrals of heat, while entropy relates to the disorder (whether thermal or positional) of a system. While these two are related, they are different concepts!

Jeremy Wei 2C
Posts: 103
Joined: Wed Sep 30, 2020 9:59 pm

### Re: Enthalpy vs Entropy

Enthalpy refers to the heat released/absorbed in the system, while Entropy refers to the disorder of the system.

Lorena_Morales_1K
Posts: 59
Joined: Wed Sep 30, 2020 10:11 pm

### Re: Enthalpy vs Entropy

No such thing as a dumb question :)
Enthalpy is the amount of internal energy contained in a compound whereas entropy is the amount of intrinsic disorder within the compound. Enthalpy is zero for elemental compounds such hydrogen gas and oxygen gas; therefore, enthalpy is nonzero for water (regardless of phase).

Sara Sandri 2B
Posts: 60
Joined: Wed Nov 18, 2020 12:18 am

### Re: Enthalpy vs Entropy

Enthalpy refers to the heat absorbed whereas entropy refers to disorder. Both are state functions.

Sofia Lombardo 2C
Posts: 100
Joined: Wed Sep 30, 2020 9:31 pm

### Re: Enthalpy vs Entropy

Entropy refers to the disorder or microstates. Enthalpy refers to the heat exchange (absorbed or released). Both entropy and enthalpy are state functions.

Gicelle Rubin 1E
Posts: 101
Joined: Fri Oct 02, 2020 12:16 am

### Re: Enthalpy vs Entropy

Basically:
Enthalpy would be the the amount of heat released/gained
Entropy would be the disorder :)

Jarrett Sung 3B
Posts: 60
Joined: Wed Sep 30, 2020 9:41 pm

### Re: Enthalpy vs Entropy

Enthalpy is more about heat transferred, while entropy is about disorder and the number of possible positions for atoms/molecules. It's important to note that they're both state functions.

Phoebe Joseph
Posts: 58
Joined: Tue Nov 17, 2020 12:19 am

### Re: Enthalpy vs Entropy

Yes, as other people have answered: enthalpy(H) is a measure of heat transfer while entropy(S) is a measure of disorder. If you say enthalpy increases (delta H is positive) then the system is using heat and needs an external supply of heat to process - this is non-spontaneous and endothermic. A negative delta H indicates that the system is releasing thermal energy - this is spontaneous and exothermic. If a system is increasing in entropy (delta S is positive) then the system is increasing in disorder - which is spontaneous. A good example of this that I learned in LS7A was using your room as an examples of increasing entropy. Naturally, your room will become more disordered (increase in entropy) as time elapses unless you put in work to stop and/or reverse this. That is how I remember what entropy is and why a positive change in entropy is spontaneous!

Hope this helps!

Return to “Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)”

### Who is online

Users browsing this forum: No registered users and 2 guests