IIT JEE , AIEEE Forum - Chemistry , Physical Chemistry

trisha

The standard electrode potentials of Zn²⁺/Zn and Ag⁺/Ag are --0.763& +0.763 respectively.find the standard potential of the cell.

I THOUGHT THE ANS IS 0.799+2(0.763)

BUT ANS GIVEN IS 0.799+0.763.CAN U EXPLAIN WHICH IS CORRECT?

chimanshu_007

are the conc. given?

Anurag.Seth

Hello Trisha,

Is your question correct?

whether Standard electrode potential of Ag is +0.763 or

+0.799.

If it be +.799 then;

Zn ²⁺ + 2e- = Zn E⁰ = -.763V (Oxidation half cell)

Ag⁺ + e- = Ag E⁰ = +.799V ( Reduction half cell)

Zn(s) + 2Ag+ = Ag + Zn ²⁺

Standard Cell Potential = Standard potential of Cathode - Standard Potential of Anode

= 0.799V - (-0.763V)

= 1.55V

Now what is your doubt?

If you're convinced with my answer do not forget to vote me, if not do reply.........

DON007

anurag has done it nicely, BUT the confusion i think TRISHA has IS that

as converting

Ag⁺ + e- = Ag ,

E⁰ = +.799V ( Reduction half cell) and note

while converting

2Ag⁺ + 2e- = 2 Ag

E⁰ is ALSO EQUAL TO +.799V

RIGHT THEREFORE IN UR

ANSWER 2* 0.799 V WAS COMING AS u were also multiplying it,

but actually , it remains +0.799V .

understood............

right

Anurag.Seth

Hey DON007,

Thanks for supporting my explanation.

trisha

DON&ANURAG PLZ TELL ME WHY 2Ag⁺

2Ag

2 is not multiplied for emf?

neeleshv

The emf is not like energy that has to be multiplied.

When a reaction is added, subtracted or multipliedor divided then same operation can be applied to energy but not emf.

Hence we have to use the formula

G= -nFE

n= n-factor

F= 96500 C

E= EMF

krishna.gopal

In emf calculations emf is energy change per unit charge. So it is energy change per electron for silver as well as zinc. So you are not reruired to multiply Ag potential by 2.

trisha

thanks

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