A voltaic cell is made by placing an iron electrode in a compartment in which the Fe2+ concentration is 2.0 ´ 10-5 M and by placing a Pt electrode in the other compartment, in which the H+ concentration is 3.4 M and = 1.00 atm.
To determine the standard cell potential of the voltaic cell, you will need to follow these steps:
1. Identify the half-reactions: In this case, the half-reaction at the iron electrode is the reduction of iron(II) ions (Fe2+(aq) + 2e- → Fe(s)), and the half-reaction at the platinum electrode is the reduction of hydrogen ions (2H+(aq) + 2e- → H2(g)).
2. Write the balanced overall equation: Multiply each half-reaction by coefficients such that the number of electrons transferred in both equations is equal. In this case, both half-reactions already have the same number of electrons. So, the overall balanced equation is:
Fe2+(aq) + 2H+(aq) → Fe(s) + H2(g)
3. Determine the standard reduction potentials: Look up the standard reduction potentials for each half-reaction. The reduction potential for the Fe2+/Fe half-reaction is given as 0.44 V, and the reduction potential for the H+/H2 half-reaction is 0.00 V.
4. Calculate the standard cell potential: Subtract the reduction potential of the anode (the electrode that undergoes oxidation) from the reduction potential of the cathode (the electrode that undergoes reduction). In this case, the anode is the Fe electrode, so its reduction potential is subtracted from the H electrode reduction potential:
E°cell = E°cathode - E°anode
= 0.00 V - 0.44 V
= -0.44 V
So, the standard cell potential of the voltaic cell is -0.44 V.