lnQ vs logQ


Moderators: Chem_Mod, Chem_Admin

vanessas0123
Posts: 100
Joined: Wed Sep 11, 2019 12:17 am

lnQ vs logQ

Postby vanessas0123 » Thu Mar 05, 2020 12:43 am

When would you use E=E°-(RT/nF)lnQ vs E=E°-(0.05916V/n)logQ ?

Also, I understand that you can substitute RT/F for 0.025963 for the ln equation when its under standard condition - 25 degree celsius. Is this correct?

Morgan Carrington 2H
Posts: 54
Joined: Wed Nov 14, 2018 12:22 am

Re: lnQ vs logQ

Postby Morgan Carrington 2H » Thu Mar 05, 2020 2:21 am

I believe the only difference between the two of these equations is that one uses the natural log and the other uses log base 10. I would just be careful to use the constants we discovered in class when interchanging between these two equations, but other than that they are the same.

Veronica_Lubera_2A
Posts: 106
Joined: Sat Sep 14, 2019 12:16 am
Been upvoted: 1 time

Re: lnQ vs logQ

Postby Veronica_Lubera_2A » Thu Mar 05, 2020 9:36 am

For the log equation you use it at standard conditions (25 degrees celsius) and the lnQ equation can be used in any situations. My personal preference is the lnQ equation since you can still get the same answer as the log one and don't have to worry about knowing when to apply it.

Katie Kyan 2K
Posts: 106
Joined: Fri Aug 09, 2019 12:16 am
Been upvoted: 1 time

Re: lnQ vs logQ

Postby Katie Kyan 2K » Thu Mar 05, 2020 10:17 am

You can use either but keep in mind that 2.303logx=lnx which is why we see two forms of the Nernst equation for standard conditions. There is E=E°-(0.05916V/n)logQ as you mentioned and E=E°-(0.025693V/n)lnQ that uses the natural log instead.

805097738
Posts: 180
Joined: Wed Sep 18, 2019 12:20 am

Re: lnQ vs logQ

Postby 805097738 » Thu Mar 05, 2020 8:58 pm

vanessas0123 wrote:When would you use E=E°-(RT/nF)lnQ vs E=E°-(0.05916V/n)logQ ?

Also, I understand that you can substitute RT/F for 0.025963 for the ln equation when its under standard condition - 25 degree celsius. Is this correct?


Yes, also I use the log one when dealing with H+ or OH- concentration; however, both can be used as long as you use the correct constants for the equation

Matthew Tsai 2H
Posts: 101
Joined: Wed Sep 18, 2019 12:20 am

Re: lnQ vs logQ

Postby Matthew Tsai 2H » Thu Mar 05, 2020 10:00 pm

I think both of these equations can basically be used interchangeably.


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

Who is online

Users browsing this forum: No registered users and 6 guests