Using the Nernst equation | Redox reactions and electrochemistry | Chemistry | Khan Academy

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Using the Nernst equation to calculate the cell potential when concentrations are not standard conditions.
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Опубликовано:

29 сен 2024

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Комментарии : 79

@ShanDRealest 4 года назад

Great aid in my pursuit of General Chemistry 2. Thanks so much 👍

@galacticnomad734 Год назад

I'm just lost on why you would add the cathode and anode when the formula is Ecathode - Eanode = Ecell.

@bobbob-in1ml Месяц назад

Ecell = Ecathode - Eanode when they're both reduction potentials *If the cathode is reduction potential, while the anode is oxidation potential, you can just add them up (you normally subtract anode because you're trying to turn a given reduction potential to an oxidation potential)

@josecarlosdelgadomalave2353 6 лет назад

When studying corrosion, I have found from many authors (and I teacher I had) that the sign in the equation is (+) not (-) and Q equals to the cations concentration. Could you explain this for me please? Is driving me crazy not knowing which sign should I use in the equation. It depends on what?

@kevindave277 8 лет назад

Thanks man.. HELPED ME.. Khan academy aka "subscribed" :)

@kodlaralemi1141 7 лет назад

abi çok iyi yaa

@alexbraggins9152 4 года назад

This was extremely helpful. Could you do more chemistry questions based on geology and geosciences in future? Thats the degree I am doing and would be super helpful. Love your way of explaining. Thanks again

@serpilserpil5203 3 года назад

Turkcesini yapamiyorum ingilizcesinden anlarim belki dedim #yks

@zopadawibur Год назад

Very clear explaination..you are the best teacher i have ever known....big big salute!!!

@abigailgoff 9 лет назад

Wouldn't Q=(products to the power of their coefficients)/(reactants to the power of their coefficients?)

@abigailgoff 9 лет назад

+Abigail Goff Kind of like you would in equilibria?

@Masrur111 9 лет назад

+Abigail Goff "Q" is called 'the reaction quotient' and "K" is called 'the equilibrium constant'. They are both calculated in the same way. Q or K = the ratio of the concentration of the products and the reactants of a reversible reaction. Second brackets [ ] are used to show concentration(usually molar concentration) of something. Molar concentration=moles/volume. There is deference between Q and K. Both are ratios of the same things, but calculated at different phases of a reaction. K is during equilibrium. That means, at equilibrium, Q=K But at other times, QK and this gives the direction of that reaction. If left untouched any reversible reaction will achieve equilibrium over time. Q(also K) is thermodynamically related to Free Energy, G. G is also related to Electric Potential Difference or Voltage. Hence the video.

@TravelWithTea8 9 лет назад

+Mostafa Al-Quadir Can I calculate Pressure and Concrentration in the same equation for Q?

@Masrur111 8 лет назад

+Top 10s The reaction quotient (Q) is a measure of the relative amounts of reactants and products during a chemical reaction at a given point in time. or simply ratio of [product] to [reactant]. If a product/reactant is dissolved in aqueous solution, we use concentrations for all of them. If all reactants/products are gaseous we use partial pressures to calculate Q. Can we use Pressures and concentrations in a single equation to solve Q? The answer is yes. But we will need to convert Pressure to concentration and vice-versa as we need. We know concentration [ ]=moles/liters =n/V. We also know PV = nRT. So, P = CRT. This is the equation for conversion. Hope that answers the question. Note: We don't include solids & liquids in the calculations, only aqueous and gaseous.

@TravelWithTea8 8 лет назад

+Mostafa Al-Quadir Do you know if it's a minus or pluss sign in Nernst Equation?

@erikaso7584 6 лет назад

As I know the E° of Zn is -0.76 not +0.76 !

@sabrinaakababrina 6 лет назад

since zn is being oxidized in this case you have to change the + to a -

@sabrinaakababrina 6 лет назад

sorry i mean the - to a +

@qazi__chemist4300 3 года назад

Sir why we use nernst equation to determine non standerd electrode potential?why we not determine electrod potential without nernst equation like Standerd elecytode potential.

@aliotako1647 4 года назад

You like god of chimestry man... From iraq i'm following you....

@bensonndendya9556 6 лет назад

You helped me some how God bless you

@abhishekranjan3941 4 года назад

I hope he could, but he doesn't exist.

@manaralhindawi2960 6 лет назад

Does anyone knows which program is used for making this video? I mean the whole drawing thing...thank you

@mdalkarim1997 7 лет назад

E0=Ecathode-Eannode E0=0.34-0.76

@mustafagoncu9488 6 лет назад

Hocam çok iyi anlatıyorsunuz yarın yazılım var iyi bir not alırım inşallah

@lauramaimarketing 8 лет назад

i freaking hate this class why am i here fml

@hans3331000 8 лет назад

i sometimes have this feeling, it's weird, like being in a small cage inside a lion enclosure or shark cage, it's kind of fun knowing you're never really in any danger. it's almost exciting, and kind of a satisfying feeling. just the feeling of being glad you're never going to be in that position for real. same with math, we are all done this nightmare of chem, but every once in a while we go back and remember the hell we went through, knowing it's never gonna hurt us again. that was weird, probably did'nt answer the question

@parth488 8 лет назад

you high bruh ?

@Vayanovic 4 года назад

@@parth488 lol

@songsart9436 5 лет назад

Why can't we use nersnt eq for electrolytic cell?

@EboniseStBrice 4 года назад

Someone please HELP!! 1) Where did 0.0592 come from? 2) Why is “n” 2 and not 4...what if electrons gained from Copper was 3 and electrons lost from Zinc was 1, then what would the new n be? PLEASE HELP 😇

@abhishekranjan3941 4 года назад

0.0592 is the value derived by putting the values of constants in the equation.

@abhishekranjan3941 4 года назад

Cause 2 moles of electrons are transferred in the reaction. And i didn't understand that 2nd one :)

@maurits00222 6 лет назад

isnt it Ln Q instead of log Q?

@williamnathanael412 3 года назад

it's base 10 logarithm. The natural log is taken care of in the 0.0592

@abhijit2575 3 года назад

Very helpful sir

@ramyaathreya8328 7 лет назад

can u please teach chemical kinetics. plzz

@Crunchyape 8 лет назад

You have the ecell wrong, you just added the ered and eox but you are supposed to subtract them. e(cell)=e(red)-e(ox)

@kalyanpamidimukkala9352 8 лет назад

+Crunchyape e(ox) is actually -0.76 so it adds up to 1.10v

@AzerothLatinoamerica 8 лет назад

+Pamadimukkala Kalyan Yeah but that part inst in the video, someone new may find this confusing

@amreshverma5747 8 лет назад

+Crunchyape we are generally given reduction potential. the formula you've given need be corrected.

@amanrayeen8217 8 лет назад

We only subtract when both of the potentials are reduction. e red ( cathode ) - e red ( anode ) is correct. Also, e red ( cathode ) + e ox ( anode ) will give the same value.

@yeefeitan5186 8 лет назад

how did u get 0.0592 V? :o

@permanentlyUnimpressed 8 лет назад

using the gas constant, Faraday's constant and standard temp 25 degrees in the same formula to replace R,T and F in E=Ecell- Rt÷nf*lnQ leaving E =Ecell- 0.059÷n*logQ do all the necessary transposition

@wooze85 6 лет назад

(8.3145*298K)/96485 does not equal 0.059.. what am i missing?

@sabrinaakababrina 6 лет назад

its a different equation, the one with 0,059 is used when the temperature is 25C the other one with RT/nF is used when the temperature is different than 25C

@sparrowspirit5301 4 года назад

@@wooze85 Your missing 2.303, multiply with the answer and u get 0.059 :)

@keyakhurana4041 3 года назад

the product of gas constant and 298 kelvin and division by faradays number gives you 0.059.

@abrarabdulrahman5907 4 года назад

Thank you.........you deserve more than a million subscribers ^_^

@padura6748 4 года назад

this tutorial' standard values (+/-) are incorrect,please correct it

@preciousmwenda 2 года назад

Is k and Q calculated in the same way?

@이동기-s8t 6 лет назад

Can we use deltaGnaught=-nFEnaught with nernst ?

@gauravganesh2007 7 месяцев назад

@liamjarrett2999 2 года назад

why do you use log instead of ln

@ahmadsyahmiadnan9279 8 лет назад

is it K =K(w) for the equilibrium constant?

@jazminsutcliff4106 7 лет назад

Can somebody help me? When I use ln(10/1) in the main formula, E=1,04 ; why do we change log for the ln shown in the previous video? I'm lost D:

@xiaowenxu1505 5 лет назад

I don't know if you still need help.I hope you are already clear about that.Yes,in the previous video,we use ln to calculate cell potential.When T is equal to 298.15 K (RT/F = 0.025693 V), we switch from ln to log (ln Q = 2.3026 log Q) to get 0.0592 in the nernst equation

@environmentalconservation5106 4 года назад

In=2.303log

@ravindersinghbedi5999 8 лет назад

In some books, the formula given is: E=E°- (2.303×RT/nf)*ln([oxidation]/[reduction]) Can some one tell me what is the 'f' given in this equation.

@shaboom812 8 лет назад

+Ravinder singh Bedi "F" is Faraday's constant, 9.648 533 99(24)×104 C mol−1

@Popereggie1993 8 лет назад

+Ravinder singh Bedi Faraday's constant

@krantidekate6490 8 лет назад

That is Faraday's constant. f=96500 C

@benjaminmangip7031 3 года назад

Thank you

@frankvalenti8350 6 лет назад

Amazing video

@jinslukose1795 3 года назад

uffffff.......

@kentkeatha6728 6 лет назад

What is -nFE??

@menzigcabashe329 7 лет назад

hi good work

@zishanismam809 7 лет назад

what happens if I get a nagetive answer?

@andyschang5890 7 лет назад

zishan ismam negative potential means you are past the equilibrium point

@juanjzavala 6 лет назад

switch cathode and anode, u have them opposite

@tseliot5294 8 лет назад

In school we use a bit of a different formula: E=E(zero)+ 0.0592/n * log((c(ox)/c(red)). And by using that, i get 1,1295 instead of 1,07. I can´t find my mistake and the formula is correct too, according to my textbook. could someone help me out?

@xiaowenxu1505 5 лет назад

firstly,the number of significant figures is wrong,and it should be - not +,you just mistook the sign.Hope you have found it out.