Consider a galvanic cell built on the following half-reactions with their standard reduction potentials shown. What is ∆G° at 25 °C for the reaction involved?

1F = 96,485 J/mol e-

Cr2O72- + 14H+ + 6e- <=> 2Cr3+ + 7H2O E° = 1.20 V

H2O2 + 2H+ + 2e- <=> 2 H2O E ° = 1.75 V

Explanation:

Cr272- + 14H+ + 6e- <=> 2Cr3+ + 7H2O E° = 1.20 V

(H2O2 + 2H+ + 2e- <=> 2H2O E ° = 1.75)x3

EMF of the cell = 1.75 x 3 - 1.20

E = 4.05 V

∆G° = - n E F  

n = 6  

E = 4.05

F = 96485

∆G° = - 6 x 4.05 x 96485

= - 2344585.5 J

when the volume of gas is   changed from   717.73 ml   to 852 ml   the temperature will   change   from 315   c to 452   c

    calculation

this is calculated using the charles law formula

that is,   v1/t1 = v2/t2

          v1=?

        t1 = 315 c   into   kelvin = 315 +273 = 588 k

        v2 = 852   ml

        t2 = 425c + 273 =698 k

make v1   the subject of the formula ( by   multiplying both side by t1)

  v1=( v2 xt1) / t2

v1= (852 ml   x 588 k)/ 698 k= 717.73 ml

there is none because earth is stationary and flat.