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Chemistry Homework Help => CBSE XI and XII Chemistry => Topic started by: Pranjal Singh on January 18, 2022, 02:37:33 AM

Title: Electrochemical cell reaction
Post by: Pranjal Singh on January 18, 2022, 02:37:33 AM
Here it is
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Title: Spontaneous reaction E cell sign and Nernst equation qualitative prediction
Post by: uma on January 23, 2022, 01:38:28 AM
For spontaneous reaction, Ecell must be positive.
You can write Nernst equation 
E cell = E0 cell - 0.059/2 [log(x1 *P2)/X2*P1)]

In our example -E0 cell=0V

now if (x1 *P2)/X2*P1) is greater than one than log value will be positive because log of number greater than 1 is always a positive integer.
Ecell will remain negative and reaction will be non spontaneous.


now if (x1 *P2)/X2*P1) is less than one than log value will be negative because log of number lesser than 1 is always a negative integer.
Ecell will become positive  and reaction will be  spontaneous.


Now check which option is giving you positive value of log.
No need of calculation as you can predict it with your basic mathematical skills.