## Laws of thermodynamics

Boltzmann Equation for Entropy: $S = k_{B} \ln W$

Vincent Leong 2B
Posts: 207
Joined: Fri Aug 09, 2019 12:15 am

### Laws of thermodynamics

What is the difference between the 2nd and 3rd law? What are their respective equations supposed to say about the system or the general word statement?

Shannon Asay 1C
Posts: 102
Joined: Fri Aug 09, 2019 12:16 am

### Re: Laws of thermodynamics

The 2nd law says that systems spontaneously go towards states of maximum entropy, which is shown by the equation, delta s=q/T. This is also demonstrated by Gibbs free energy equation because systems that are exothermic and have high entropy are spontaneous. For the third law, it's saying that as the temperature drops to 0, entropy also approaches 0. The limit equation directly shows this.

Posts: 103
Joined: Sat Aug 17, 2019 12:18 am

### Re: Laws of thermodynamics

Shannon Asay 1C wrote:The 2nd law says that systems spontaneously go towards states of maximum entropy, which is shown by the equation, delta s=q/T. This is also demonstrated by Gibbs free energy equation because systems that are exothermic and have high entropy are spontaneous. For the third law, it's saying that as the temperature drops to 0, entropy also approaches 0. The limit equation directly shows this.

For entropy to approach 0 (third law), the absolute temperature of a perfect crystal must also approach 0. This is because a perfect crystal will have zero positional disorder and when the temperature is 0, zero thermal disorder. If just the temperature was zero, but positional disorder was still present, entropy would be a non-zero value.

Mai V 4L
Posts: 111
Joined: Fri Sep 28, 2018 12:23 am

### Re: Laws of thermodynamics

Can someone please share their favorite youtube videos/graphics to help remember this? Thanks.

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