when you are given two half reactions and you are told to calculate net E^O, would you find the voltage for each reaction and subtract the two to get the answer?
If the values are not at standard state AND one is an oxidation half cell while the other is a reduction half cell, you calculate the voltage of each then ADD the two together.
one is oxidation and the other is reduction but they are at standard conditions though so how does that change things?
Eo oxidan half + Eo redn half = Eo cell
thank you =)
To calculate the net standard electrode potential (E^O) for a redox reaction using half-reactions, you need to follow these steps:
1. Write the two half-reactions: Start by writing the oxidation and reduction half-reactions separately. Ensure that the number of electrons exchanged in both reactions is the same so that they can cancel out in the final net reaction.
2. Balance the half-reactions: Make sure that the number of atoms and charges are balanced on both sides of the half-reactions. This involves adjusting coefficients and adding water (H2O), hydrogen ions (H+), or hydroxide ions (OH-) as necessary.
3. Determine the standard electrode potentials (E^O) for each half-reaction: The E^O values are usually given in tables. Look up the E^O value for each half-reaction. The E^O value represents the potential difference in volts between the half-reaction and the standard hydrogen electrode (SHE), which is assigned an E^O value of 0 volts.
4. Add or subtract the half-reactions: Depending on the overall balanced equation, add or subtract the half-reactions so that electrons cancel out, and you have a balanced net reaction. You can multiply the half-reactions by coefficients if necessary.
5. Calculate the net E^O: The net E^O for the reaction can be determined by adding or subtracting the E^O values of the half-reactions, based on the stoichiometric coefficients from step 4. If necessary, invert the E^O values of the half-reactions to match the stoichiometric coefficients.
So to answer your question, you do not simply subtract the voltage of each half-reaction to get the net E^O. You need to balance the half-reactions, look up the standard electrode potentials, and then combine the half-reactions to obtain the net E^O value for the overall reaction.