Relationship between entropy and spontaneity

Moderators: Chem_Mod, Chem_Admin

Mary Becerra 2D
Posts: 53
Joined: Fri Sep 29, 2017 7:06 am

Relationship between entropy and spontaneity

Postby Mary Becerra 2D » Sat Jan 27, 2018 9:20 pm

In Friday's lecture, Lavelle had on is powerpoint, "In any spontaneous process there is an increase in entropy." Does this mean that in any non-spontaneous process there is a decrease in entropy?

Nisarg Shah 1C
Posts: 54
Joined: Sat Jul 22, 2017 3:00 am

Re: Relationship between entropy and spontaneity

Postby Nisarg Shah 1C » Sat Jan 27, 2018 10:29 pm

Not necessarily, as we learn later, Gibbs Free Energy or (G) determines the spontaneity of a reaction. It is determined by change in enthalpy, absolute temperature, and entropy: . If (G) is negative, the reaction is spontaneous.

Srbui Azarapetian 2C
Posts: 54
Joined: Thu Jul 13, 2017 3:00 am
Been upvoted: 2 times

Re: Relationship between entropy and spontaneity

Postby Srbui Azarapetian 2C » Sun Jan 28, 2018 1:39 pm

To add to the previous answer, the spontaneity, or Gibbs free energy depends on entropy and enthalpy. Positive entropy and negative enthalpy means the reaction is spontaneous at all temperatures. Positive entropy and enthalpy means the reaction is spontaneous at high temperatures. Negative entropy and enthalpy means the reaction is spontaneous at low temperatures. Negative entropy and positive enthalpy means the reaction is not spontaneous at any temperature.

Cyianna 2F
Posts: 34
Joined: Wed Nov 16, 2016 3:04 am

Re: Relationship between entropy and spontaneity

Postby Cyianna 2F » Sun Jan 28, 2018 3:13 pm

Spontaneity refers to any reaction that favors products over reactants. Because so much energy is used to make the products, there's always going to be a decrease in free energy (Gibbs free energy). That is why is negative. Entropy must stay positive (or increase) in order to keep negative.


Return to “Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)”

Who is online

Users browsing this forum: No registered users and 1 guest