[sofiaAr]

given 2 half cell reactions and their potential:
H2O2(aq) + 2H+(aq) + 2e- 2H2O(l)    E = 1.78 V
O2(g) + 2H+(aq) + 2e- H2O2(aq)       E  = 0.68 V
A. Write down the overall reaction that occurs galvanic electrochemical cell built for two
    Cell halves .
B. Write an expression for Q Nernst equation.
C. Write the cell notation .
D. Calculate the cell voltage if the initial concentrations of the components of the cell are :
    [H2O2(aq) )] = 1.5 M
    [H+(aq)] =1.0 M 
    And set the value equation 1 bar pressure oxygen gas .

I really need help, thanks!!

[Borek]

You have to show your attempts at solving the problem to receive help, this is a forum policy.

[sofiaAr]

OKAY :
A.
     H2O2 +2H+ + 2e-  2H2O E°= 1.78 V
     H2O2  O2 + 2H+ + 2e E°=-0.68 V
    2H2O2(aq) --> O2(g) + 2H2O(l) E°= 1.78 V -0.68 V = 1.10 V

B.
    E=1.10V-0.05916V/2*logQ


C.
    Cathode: Pt electrode; H2O2 and H+ in solution
     Anode: Pt electrode; O2(g) bubbled in, H2O2 and H+ in solution

D.
    ((( I'm not sure what to do )))

[Borek]

Can you use Nernst equation and concentrations given to calculate real (formal) potentials for each half cell?

[sofiaAr]

Is that right?

Nernst Equation: E = 1.10 – 0.0592/2 *log O2/ [H2O2]^2
                             E = +1.10 - 0.0592/2*log 1/(1.5)^2


thanks