1 Answer
Jul 18, 2017
You'd start from the expression for the change in Gibbs' free energy, #DeltaG# , relative to a reference, #DeltaG^@# , at standard pressure and a convenient temperature:
Two reactions with their balanced equations, K1 and K2 are given. Students are to calculate the K1 and K2 for the rearranged, flipped, and re-organized equations. And from there, calculate the overall Keq. Voiceover Our goal is to calculate the equilibrium constant K for this reaction, so for this reaction right here. Now we're gonna use the standard reduction potentials to do so. So in the previous video, we talked about the relationship between the equilibrium constant K and the standard cell potential.
Calculating an Equilibrium Constant from the Free Energy Change. If we know the standard state free energy change, G o, for a chemical process at some temperature T, we can calculate the equilibrium constant for the process at that temperature using the relationship between G o and K. Rearrangement gives In this equation.
where:
#Q# is the reaction quotient for the current state of the reaction.#R# and#T# are known from the ideal gas law.#RTlnQ# describes the shift in the free energy in reference to standard pressure and the chosen temperature (usually#25^@ 'C'# for convenience).
At chemical equilibrium, the reaction has no tendency to shift in either direction, so the change in Gibbs' free energy is zero, i.e.
Thus, with #Q = K# as well at equilibrium,
Ecamm Live puts the power of Facebook Live, YouTube Live, Periscope, and Twitch video streaming at your fingertips. Your New Broadcasting Studio Everything's here, including support for multiple cameras, Blackmagic HDMI capture devices, iPhone and Mac screensharing, and more. Ecamm live software. Join The Community. Network with like-minded content producers, marketing experts, and live streamers in our Ecamm Live Facebook Community. Our dynamic online community is the perfect place to ask questions, share tips and tricks, swap stories, and get advice from seasoned experts.
And usually the other kind of calculation of this kind is to solve for #K_(eq)# .
where #'exp'(x) = e^x# .
Related questions
Impact of this question
You can reuse this answer
Creative Commons License
Creative Commons License
1 Answer
Aug 21, 2016
Explanation:
The equilibrium constant of a reaction under the general form:
can be calculated by the general expression of #K_(eq)# as follows:
Therefore, #K_(eq)=([C][D])/([A][B])=K_c#
If the reactants and products are gases, we can also calculate the equilibrium constant using pressures, in this case the equilibrium constant is called #K_P# :
Note that, if any of the reactants or products are in the liquid or solid states, these are not included in the expression of the equilibrium constant.
For example, consider the following general reaction:
How To Find The Equilibrium Constant
Thus, the equilibrium constant #K_c# expression is written as:
or using pressures as:
Note that aqueous state is treated as gases, however, we don't calculate #K_P# in this case from pressures, therefore, we only find #K_c# :
How To Calculate Keq Values With Pka
This lesson could be even discussed with more details. I recommend that you watch the following video which is one of an entire chapter of five videos on chemical equilibrium:
Chemical Equilibrium | The Equilibrium Conditions.
Chemical Equilibrium | The Equilibrium Conditions.
Related questions
Impact of this question
You can reuse this answer
Creative Commons License
Creative Commons License