Gibbs Energy and Reaction Quotient

In summary, the conversation discusses the confusion around the Gibbs energy of a reaction involving pure substances. It is established that at the start of the reaction, the reaction quotient is zero, leading to an undefined change in Gibbs energy. The possibility of the change being infinitely negative is also considered, suggesting that the formation of C is highly favorable.
  • #1
llabesab16
5
0
I have been putting some thought into understanding Gibbs energy but I can't quite figure one thing out. Here is my dilemma:

Say that someone wants to react A with B to form C, and they mix pure A with pure B. At the moment the reaction starts, there is no C in the mixture (is this correct?). If the reaction quotient is [C]/[A], then shouldn't the reaction quotient equal zero at the beginning of the reaction? If that is the case, then wouldn't the change in Gibbs energy be undefined at the beginning of the reaction if deltaG = deltaG(standard) + RTln(Q)?

Thanks for your help!
 
Chemistry news on Phys.org
  • #2
Sure. You could also think of it as being infinitely negative, so the formation of C will be very favorable.
 

1. What is Gibbs Energy?

Gibbs Energy, also known as Gibbs free energy, is a thermodynamic quantity that measures the amount of energy available to do useful work in a system. It takes into account both the enthalpy (heat content) and entropy (disorder) of a system, and is often used to determine whether a chemical reaction is spontaneous or not.

2. How is Gibbs Energy related to Reaction Quotient?

Gibbs Energy is related to Reaction Quotient (Q) through the equation ΔG = ΔG° + RTln(Q), where ΔG is the change in Gibbs Energy, ΔG° is the standard change in Gibbs Energy, R is the gas constant, T is the temperature in Kelvin, and Q is the reaction quotient. This equation allows us to predict the direction of a chemical reaction and whether it is at equilibrium or not.

3. What is the significance of a negative Gibbs Energy?

A negative Gibbs Energy indicates that a reaction is spontaneous, meaning that it will occur without the need for external energy. In other words, the reactants have more energy than the products, and the reaction will proceed in the forward direction to reach a more stable state.

4. Can Gibbs Energy be zero?

Yes, Gibbs Energy can be zero when a reaction is at equilibrium. This means that the system has reached a balance between the forward and reverse reactions, and there is no net change in the concentrations of reactants and products. At equilibrium, ΔG = 0 and Q = K (the equilibrium constant).

5. How does temperature affect Gibbs Energy and Reaction Quotient?

Temperature has a significant impact on both Gibbs Energy and Reaction Quotient. As temperature increases, the value of Q changes, which in turn affects the value of ΔG. This means that the spontaneity of a reaction can change with temperature. Additionally, the value of ΔG° is dependent on temperature, which can alter the direction and speed of a reaction.

Similar threads

Gibbs free energy of activation and activation energy
    • Chemistry
Replies
4
Views
1K
Is it possible to have an "Eternal reaction" by mixing the products?
    • Chemistry
Replies
7
Views
1K
Trouble with Gibbs Free Energy & Equilibrium Constant Calc.
    • Chemistry
Replies
3
Views
2K
Confused about gibbs free energy
    • Chemistry
Replies
4
Views
3K
Gibbs Free Energy Change/Entropy
    • Chemistry
Replies
4
Views
3K
How does enthelpy change as the reaction proceeds?
    • Chemistry
2
Replies
37
Views
6K
Questions regarding Gibbs energy changes
    • Chemistry
Replies
29
Views
2K
How Do You Calculate ΔG for a Reaction at Non-Standard Conditions?
    • Biology and Chemistry Homework Help
Replies
1
Views
2K
Why is Qir < than Qr? Carnot cycle and change in G
    • Thermodynamics
Replies
34
Views
4K
Gibbs free energy going to zero (equilibrium)
    • Chemistry
Replies
1
Views
2K

Hot Threads

Recent Insights

Back
Top