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.

 

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