If a reaction has an equilibrium constant K 6 1, is E° posi-tive or negative? What is the value of K when E° = 0 V?

Video transcript

Welcome back, everyone. We need to predict a sign of our electrode potential when our equilibrium constant of our reaction is greater than one and determine the value of K if our reduction potential is equal to 0V. So let's begin by recalling our nursed equation which we should recall relates the standard electrode potential of a cell, which is represented as a degree under standard conditions to the gibbs free energy of an electrochemical reaction. So this is equal to the following quotient where we take our constant, specifically R gas constant R multiplied by the temperature in Kelvin divided by our moles of electrons involved in the reaction multiplied by faraday's constant. And let's just have two big parentheses actually. And then we would have the Ln of our equilibrium constant for the reaction. So just to be clear, our is our gas constant. Our temperature is in Kelvin and N is our moles of electrons involved in the reaction. And then F is faraday's constant. And then we have K our equilibrium constant for our reaction. So we use this equation to calculate the potential of an electrode in an electrochemical cell that is under nonstandard conditions. And we're told that the reduction potential degree is equal to 0V. And so we need to find the value of K. Now, based on our equation, we can see that we have a direct relationship where our self potential degree is directly proportional to our equilibrium constant K when we take the Ln of our equilibrium constant. So in other words, the self potential is under standard conditions is directly proportional to the L N F K. And so with this understood, if we know that our self potential is equal to zero volts, then that means that the Ln of our equilibrium constant K because of this direct relationship should also equal zero volts. And so we would say that therefore what would give us, what value of K would give us the L N F K being zero volts. Well, we can say that their four K should equal one. And so the only answer choice that corresponds to everything that we've outlined would B choice C which says that when K, our equilibrium constant is greater than one hour reduction potential under standard conditions is also going to be positive. And so if our cell potential or reduction potential under standard conditions is equal to zero volts, then are equally been constant. Must equal one, which is what we outlined here, which proved that the Ln of one equal zero volts A K A, the L N F K is equal to zero volts and so c would be our final answer. I hope everything I reviewed was clear. If you have any questions, please leave them down below and I'll see everyone in the next practice video.