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The standard reduction potential for Zn...

The standard reduction potential for `Zn^(2+)//Zn` is -0.76V. Write the reactions occurring at the electrodes when coupled with NHE or SHE.

A

increase of 59mV

B

decrease of 59mV

C

increase of 25.5mV

D

decrease of 2.95V

Text Solution

Verified by Experts

The correct Answer is:
B
`E_(Zn^(2+)//Zn)=E_(Zn^(2+)//Zn)^(@)-(0.059)/(2)"log"(1)/(|Zn^(2+)|)`
`E_(Zn^(2+)//Zn)=E_(Zn^(3+)//Zn)+0.0295"log"C`
When solution is diluted 100 times.
`E_(Zn^(2+)//Zn)=E_(Zn^(2+)//Zn)^(@)+0.0295"log"(C)/(100)`
`=E_(Zn^(2+)//Zn)^(@)+0.0295"log" C-0.0295xx2`
`=E_(Zn^(2+)//Zn)-0.059`
`E_(Zn^(2+)//Zn)-E_(Zn^(3+)//Zn)=-0.059V=-59mV`
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