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### spontaneity

Posted: Wed Feb 12, 2020 3:06 pm
What is most important in deciding if a reaction is spontaneous (ex enthalpy, entropy, Gibbs free energy)?

### Re: spontaneity

Posted: Wed Feb 12, 2020 3:14 pm
Gibbs Free Energy. If delta G is negative you know that the forward reaction is spontaneous.

### Re: spontaneity

Posted: Wed Feb 12, 2020 8:53 pm
Gibbs free energy change determines if a reaction is spontaneous under the conditions of constant pressure and constant temperature

### Re: spontaneity

Posted: Thu Feb 13, 2020 4:33 pm
Gibbs Free Energy (delta G) gives information about the spontaneity of a reaction. If deltaG<0, then the reaction is spontaneous.

### Re: spontaneity

Posted: Thu Feb 13, 2020 4:35 pm
If delta G (Gibbs free energy) is negative then you know that it was spontaneous.

### Re: spontaneity

Posted: Thu Feb 13, 2020 4:38 pm
Gibbs free energy will allow you to determine if the reaction is spontaneous or not (based on the sign). Also enthalpy can be used, as negative enthalpy means the reaction is exothermic since it is releasing heat.

### Re: spontaneity

Posted: Sat Feb 15, 2020 4:54 pm
Definitely Gibbs Free energy (delta G)! If delta G is negative then the reaction is spontaneous, but if it’s positive it is not.

### Re: spontaneity

Posted: Sat Feb 15, 2020 5:08 pm
Gibbs Free Energy is definitely the best indicator of spontaneity as it takes into account entropy and enthalpy.

### Re: spontaneity

Posted: Sat Feb 15, 2020 10:14 pm
Gibbs free energy is one of the easiest ways to determine whether a reaction is spontaneous or not. A negative delta G is spontaneous (exergonic) and a positive delta G is not spontaneous (endergonic).

### Re: spontaneity

Posted: Sat Feb 15, 2020 10:16 pm
annikaying wrote:What is most important in deciding if a reaction is spontaneous (ex enthalpy, entropy, Gibbs free energy)?

Personally, I think that Gibbs free energy is the best indicator because it combines enthalpy and entropy. Moreover, it's extremely clear cut: if delta G is negative, it is spontaneous; if delta G is positive, it is not spontaneous. However, this does not mean that you can't estimate if a reaction is spontaneous or not using enthalpy or entropy. It's just that Gibbs free energy is much more clear cut.

### Re: spontaneity

Posted: Sun Feb 16, 2020 3:00 am
A negative delta G means that the reaction is spontaneous.

### Re: spontaneity

Posted: Sun Feb 16, 2020 9:04 am
As everyone above said, Gibbs free energy is how you determine if a reaction is spontaneous or not. However, it might be important to remember that the reason Gibbs free energy is so clear cut is that it’s because it’s based off total entropy which is always increasing.

### Re: spontaneity

Posted: Sun Feb 16, 2020 11:14 am
Delta G is the greatest determiner of whether a reaction will be spontaneous or not. If delta G is negative, then the reaction is spontaneous. You could also use the equation DeltaG= DeltaH- T*DeltaS, given either DeltaH or DeltaS, to see what values need to be in order to produce a spontaneous reaction.

### Re: spontaneity

Posted: Sun Feb 16, 2020 11:34 am
Aside from delta G, a reaction is spontaneous if delta H is negative and delta S is positive.

### Re: spontaneity

Posted: Sun Feb 16, 2020 1:06 pm
jisulee1C wrote:Gibbs Free Energy. If delta G is negative you know that the forward reaction is spontaneous.

Why is it Gibbs Free Energy vs, using enthalpy or entropy.

### Re: spontaneity

Posted: Sun Feb 16, 2020 1:08 pm
Gibbs free energy, which is determined by enthalpy and entropy.

### Re: spontaneity

Posted: Sun Feb 16, 2020 1:13 pm
If a reaction has an increase in entropy or a decrease in enthalpy, then it is more likely to be spontaneous. To compute the actual value you need to check if the Gibbs free energy of a reaction is negative and to do that you use the equation delta G=deltaH-T*deltaS

### Re: spontaneity

Posted: Sun Feb 16, 2020 2:15 pm
Why exactly does delta G have to be negative to be considered spontaneous?

### Re: spontaneity

Posted: Sun Feb 16, 2020 3:18 pm
Gibbs free energy has to be negative. B/c delta G= Delta H - T*DeltaS the others contribute to delta G

### Re: spontaneity

Posted: Sun Feb 16, 2020 3:22 pm
Natalie Benitez 1E wrote:Why exactly does delta G have to be negative to be considered spontaneous?

If delta G is negative that means it is going from higher energy(reactants) to lower energy (products). If it is going from high to low, you need very little (if any input of energy) so it will happen spontaneously.
On the other hand when Delta G is positive, it is going from lower energy of reactants to higher energy of products. Because it is going from low to high, it needs an input of energy. The reaction will not take place unless there is this input which. is why it is not spontaneous

### Re: spontaneity

Posted: Sun Feb 16, 2020 5:55 pm
Gibbs free energy is usually a delta, so final minus initial. When delta G is negative the products have less gibbs free energy, making the reation spontaneous

### Re: spontaneity

Posted: Sun Feb 16, 2020 5:56 pm
If delta g, gibbs free energy, is a negative value, then the reaction in question can be determined to be spontaneous

### Re: spontaneity

Posted: Sun Feb 16, 2020 11:04 pm
To add on, when Gibbs free energy is negative that means that according the equation for gibbs free energy, delta S or change in entropy is positive and if change in entropy is positive, it means that a process is spontaneous.

### Re: spontaneity

Posted: Wed Feb 19, 2020 9:15 pm
If the delta g value is negative then the reaction is considered spontaneous.

### Re: spontaneity

Posted: Sat Feb 29, 2020 4:48 pm
when delta g is negative, the reaction is spontaneous and vice versa with positivity.

### Re: spontaneity

Posted: Sat Feb 29, 2020 5:21 pm
Gibbs free energy! If the delta g is negative then it is going to be spontaneous.

### Re: spontaneity

Posted: Sat Feb 29, 2020 6:26 pm
gibbs free energy!!

### Re: spontaneity

Posted: Sun Mar 01, 2020 12:00 pm
delta G is the most forward way to determine if the reaction is spontaneous or not.

### Re: spontaneity

Posted: Sun Mar 01, 2020 5:11 pm
Gibbs free energy is the best and most accurate way to tell whether a reaction is spontaneous, but using the equation delta G= delta H- T*delta S, it is possible to see what values of delta H and delta S gives a a negative delta G value.

### Re: spontaneity

Posted: Sun Mar 01, 2020 9:08 pm
Gibbs free energy is the best determinant. I think it's best since it includes both entropy and enthalpy in its formula. If it's negative it is spontaneous

### Re: spontaneity

Posted: Sun Mar 01, 2020 9:34 pm
Gibbs free energy can help determine spontaneity.

### Re: spontaneity

Posted: Sun Mar 01, 2020 9:40 pm
Gibbs free energy under conditions of constant temperature and pressure! your delta G must be negative because that is the energy free to do work!

### Re: spontaneity

Posted: Mon Mar 09, 2020 9:55 pm
the spontaneity does depend on the enthalpy and entropy as seen in the equation

### Re: spontaneity

Posted: Wed Mar 11, 2020 10:38 pm
Gibbs free energy is defined by a combination of enthalpy, temperature, and entropy. If Gibbs free energy is negative, that means the reaction is spontaneous, and if it is positive, the reaction will not be spontaneous. Note, spontaneity does NOT mean that the reaction will just proceed quickly, just that it is thermodynamically favorable. The largest factor is definitely enthalpy. Entropy can play a small role, but enthalpy usually dominates the spontaneity of a reaction.

### Re: spontaneity

Posted: Wed Mar 11, 2020 10:40 pm
gibbs free energy!!!!