For the following electrochemical cell at 289 K, Pt ( s ) | H 2 ( g , 1  bar )   | H + ( aq ,…

For the following electrochemical cell at 289 K,
Pt( s )| H 2 (g,1 bar) | H + (aq,1M)|| M 4+ (aq.), M 2+ (aq.)| Pt(s)
Ecell=0.092 V when M2+aq.M4+aq.=10x
Given: EM4+/M2+0=0.151 V ;2.303RTF=0.059
The value of x is -
  1. -2
  2. -1
  3. 1
  4. 2

Solution

At anode : H2g2H+aq+2e-
At cathode : M4+aq+2e-M2+aq 
Net cell reaction : H2g+M4+aq2H+aq+M2+(aq)
E cell = E cell 0 0.059 2 log [ M 2+ ] [ H + ] 2 [ M 4+ ]( P H 2 )
Now, Ecell=EM4+/M2+0-EH+/H20-0.059n.logH+2 M2+PH2.M4+
0.092=0.151-0-0.0592.log12×M2+1×M4+
M2+M4+=102x=2

Asked in: JEE Advanced 2016 (Paper 2)

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