Question

a.) A voltaic cell is constructed in which the cathode is a standard hydrogen electrode and the anode is a hydrogen electrode (P(H₂) = 1 atm) immersed in a solution of unknown [H⁺]. If the cell potential is 0.204 V, what is the pH of the unknown solution at 298 K?

b.) An electrochemical cell is constructed in which a Cr³⁺(1.00 M)|Cr(s) half-cell is connected to an H₃O⁺(aq)|H₂(1 atm) half-cell with unknown H₃O⁺ concentration. The measured cell voltage is 0.366 V, and the Cr³⁺|Cr half-cell is the anode. What is the pH in the H₃O⁺|H₂ half-cell? The standard reduction potential for the Cr³⁺|Cr half-cell is -0.740 V.

c.) Consider the following cell reaction:

Ni(s) + 2 H⁺(? M) --> Ni²⁺(1.00 M) + H₂(g)(1.00 atm)

If the cell potential at 298 K is 0.115 volts, what is the pH of the hydrogen electrode?