## Q

$E_{cell} = E_{cell}^{\circ}-\frac{RT}{nF}\ln Q$

Ethan Vuong 3G
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### Q

Is Q essentially the same thing as K but when the equation is not in equilibrium?

Niyanta Joshi 1F
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### Re: Q

Q is usually used to determine which direction the reaction will have to shift towards to reach chemical equilibrium.

Joshua Hughes 1L
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### Re: Q

Yep. its the same thing except its the concentrations of some reaction that isn't at equilibrium and we use Q to compare to K to see how the reaction will shift or change as it heads towards equilibrium

Tiffany 1B
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### Re: Q

Yeah, Q is the concentrations of products over reactants just like K, except Q represents any point in the reaction while K is specifically at equilibrium.

Kevin Ru 1D
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### Re: Q

If Q is greater than K, the reaction will shift to the left and if it's less than K then the reaction will shift to the right!

Nora Sharp 1C
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### Re: Q

Q is similar to K (products/reactants) but the amounts of products and reactants used in calculating Q represent the reaction when it is not at equilibrium and is instead in the process of reaching equilibrium. It allows us to compare the current ratio of products and reactants at a certain point in time to K, which should be the final ratio of products/reactants.

ClaireHW
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### Re: Q

How exactly is Q or K written in terms a cell diagram?

(Claire Woolson Dis 1K)

Nora Sharp 1C
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Joined: Sat Jul 22, 2017 3:00 am

### Re: Q

Q and K are written with the same scheme that we learned last quarter.

for reaction aA + bB ---> cC + dD,
K = ([C]^c * [D]^d)/([A]^a * [B]^b)

In a galvanic cell, use the equation for the full reaction (combine the half reactions) to get your products and reactants. The substances that are favored to form should be used as your K equation products. When using K or Q for a concentration cell, consider the side with the higher concentration to be the reactant.

Return to “Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)”

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