Nernst Equation

[CANgnome]

So, it seems like there is just a little blurb on this in both chad, kbb, and destroyer. How much are we supposed to know about nernst equation in electrochemistry?

E = E* - 0.0592/n x log Q

(Amp)(Time)/(F) = moles

gibbs = -nFE*

I only really know what equation 2 is about. The rest I have yet to see it used on topscore, achiever, destroyer, or kbb exams

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[sfoksn]

Need to know all 3.

 

[iamgosu]

what's the second equation?
i've never seen it before in my life

 

[CANgnome]

the number of moles of solid X produced if you subject X in its ionic form to a certain amount of amps and time, n = number of electrons involved in the reaction.

actually, i looked over everything for about half an hour and it is pretty easy.

gibbs = -nFE is the relationship between gibbs and E*cell, or emf, to show whether the reaction will be spontaneous or not. The equation is kind of intuitive since a positive Ecell will always be spontaneous, in a voltaic/galvanic cell.

the first equation is when you have different concentrations, temperature, etc and want to find out how the new E is different from standard condition E.

 

[dl2501]

the number of moles of solid X produced if you subject X in its ionic form to a certain amount of amps and time, n = number of electrons involved in the reaction.

actually, i looked over everything for about half an hour and it is pretty easy.

gibbs = -nFE is the relationship between gibbs and E*cell, or emf, to show whether the reaction will be spontaneous or not. The equation is kind of intuitive since a positive Ecell will always be spontaneous, in a voltaic/galvanic cell.

the first equation is when you have different concentrations, temperature, etc and want to find out how the new E is different from standard condition E.

Hey old post, but.... What if the reaction was Al + Cu +2 -> Al +3 + Cu , and there is 3-e by Al and 2-e by Cu, total of 6 e- transferred... Would n be 6 e-?

 

[DAT Destroyer]

So, it seems like there is just a little blurb on this in both chad, kbb, and destroyer. How much are we supposed to know about nernst equation in electrochemistry?

E = E* - 0.0592/n x log Q

(Amp)(Time)/(F) = moles

gibbs = -nFE*

I only really know what equation 2 is about. The rest I have yet to see it used on topscore, achiever, destroyer, or kbb exams

For the DAT exam, I would at least have a BASIC understanding of this important electrochemistry equation. Here is what you need to know and we can avoid doing any calculations. Fair enough ? The E zero term is the cell voltage operating under standard conditions of 1 atm, 25 C, pH of 1, and all solutes at 1M. When the concentrations and reactions conditions such as pH change, we need to use this NERNST equation. For example, if we were dealing with an experiment in which Zinc ions were 0.002M and Copper ions were at 0.03M, we would then employ this equation to get a more accurate value for the Cell potential ( cell voltage ). Thus the bottom line is this.....we use the Nernst equation to find cell voltage when conditions are different from the standard conditions !!!

I hope this helps.

Dr. Romano

 

[dl2501]

@orgoman22 It definitely helps more conceptually, but I am still a bit confused in terms of how to use the equation, particularly what the "n" in the equation denotes. In Chad's video there was a transfer of two electrons for a reaction involving Cu and something else and it was easy to see that 2 e- balanced the equation. But for
" Al + Cu +2 -> Al +3 + Cu" it is a total of 6e- that is being transferred, so would n = 6 in this case? (assuming we are not at standard conditions)

 

[DAT Destroyer]

@orgoman22 It definitely helps more conceptually, but I am still a bit confused in terms of how to use the equation, particularly what the "n" in the equation denotes. In Chad's video there was a transfer of two electrons for a reaction involving Cu and something else and it was easy to see that 2 e- balanced the equation. But for
" Al + Cu +2 -> Al +3 + Cu" it is a total of 6e- that is being transferred, so would n = 6 in this case? (assuming we are not at standard conditions)

When using the Nernst equation, think of n as the least common denominator. If one half reaction has 2e- and the other 3e-.....use n=6. Lets do two more together.....If one equation has 3e- and another has 1e-, what is n ? I hope you said 3. One more,,,,,If one half reaction has 2 e- and another has 5 e- what is n ? I hope you said 10 !!!! If you need more clarity, pick up a text book written by a PhD chemist. Zumdahl, Ebbing, and Chang are fine choices with easy reading. I hope this helps.

 

[dl2501]

@orgoman22 Thank you so so much, it was indeed helpful. I really appreciate it!