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Nernst Equation Calculator

Nernst Equation Calculator

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The Nernst equation calculator generally tells you about the relation between Gibb’s Free Energy DG and the Electro motive force of a chemical system which is defined as galvanic cell. In terms of reaction it is represented as follows:-

p P + q Q = r R + s S

Example 1

Evaluate the EMF of the below mentioned cell

Zn(s) | Zn2+ (0.044 M) || Zn2+ (4.4 M) | Zn(s)

Solution:-

1) Reduction and Oxidation Reaction :-

Zn2+ (4.4 M) + 2 e = Zn

Zn = Zn2+ (0.044 M) + 2 e

--------------------------------------------

Zn2+ (4.4 M) = Zn2+ (0.044 M), DE° = 0.00 - -

So the above equation is the net reaction.

By the Nernst equation:

0.0592       (0.044)
DE = 0.00 - ------- log --------
2          (4.4)

= (-0.296) (-2.0)

= 0.0592 V

Example 2

Prove by steps that voltage is not affected by multiplying the reaction equation by a any number

which is positive.

Solution:-

Let us assume the cell:-

Mg | Mg2+ || Ag+ | Ag

In this case the reaction is as follows:-

Mg + 2 Ag+ = Mg2+ + 2 Ag

Now Applying the Nernst equation

0.0592       (Product) Mg2+]
DE = DE° - ------ log -----------------
2        (Reactant) [Ag+]2

Now we need to multiply the equation of reaction by 2, we will find the following equation:-

2 (Mg + 2 Ag+) = 2 (Mg2+ + 2 Ag)
2 Mg+ 4 Ag+ = 2 Mg+ + 4 Ag

Now we can see that there are 4 electrons intricate in this equation and hence n = 4 in the equation

0.0592     [Mg2+]2
DE =  DE°  - ------ log --------
4        [Ag+]4

This equation can further be simplified as below:-

0.0592     [Mg2+]
DE = DE° - ------ log --------
2        [Ag+]2

Hence we see that the result remains unchanged.