The cell potential for the cell Zn(s) + 2H+(? M) LaTeX: \longrightarrow⟶ Zn2+(1.3 M) + H2(g) (8 atm) is observed to be 0.68 V. What is the pH in the H+/H2 half-cell? Reduction potential for H2(g)/H+(aq) is 0.00 V, for Zn(s)/Zn2+(aq) is -0.76 V. Enter number to 2 decimal places.

pH in the half cell is 0.84.

Explanation:

Oxidation:

Reduction:

-------------------------------------------------------

Overall:

 = (0.00 V) + (0.76 V) = 0.76 V

According to Nernst equation for this cell reaction at room temperature (298 K):              

where, is cell potential, n is number of electron exchanged, is pressure of in atm and species under third bracket represent molarity of the respective species.

So,

pH = = -log(0.1436) = 0.84

i think 4.44 moles