Video Transcript
The standard electrode potential of the half-cell equation F2 gas plus two e minus in equilibrium with two F minus aqueous is measured to be positive 2.87 volts. What does this tell you about the oxidizing or reducing ability of the chemical species on the left-hand side of the equation? (A) It is a strong oxidizing agent. (B) It is a strong reducing agent.
The standard electrode potential, also called the standard reduction potential, is the potential difference between the standard hydrogen electrode and a half-cell under standard conditions. Standard conditions include one-molar solutions, gases with a pressure of one atmosphere, and a temperature of 25 degrees Celsius. We can measure the standard electrode potential by connecting the standard hydrogen electrode to the half-cell we’re interested in measuring and then measuring the voltage using a voltmeter. We do this because the voltmeter can only tell us the potential difference between the two half-cells. This means we can’t directly measure the oxidizing or reducing ability of a half-cell; we need a standard to measure all half-cells against.
When we determine the voltage reading, it will either be positive or negative. A positive voltage reading means that the reduction potential of the other half-cell is greater than the reduction potential of the standard hydrogen electrode. In other words, electrons will flow from the standard hydrogen electrode to the other half-cell. The standard hydrogen electrode will be oxidized, making it the anode. And the other half-cell will be reduced, making it the cathode. In this case the other half-cell has a greater tendency to accept electrons than the standard hydrogen electrode, making it a better oxidizing agent.
When the voltage reading between the standard hydrogen electrode and the other half-cell is negative, the opposite is true. In this case, the reduction potential of the standard hydrogen electrode is greater than the reduction potential of the other half-cell. This means that electrons will now flow from the other half-cell to the standard hydrogen electrode. This time, the standard hydrogen electrode will be reduced, so it is the cathode. And the other half-cell will be oxidized, making it the anode. In this case, the other half-cell is being oxidized, so it is a better reducing agent.
The standard electrode potential of the half-cell in this question was measured to be positive 2.87 volts. As we’ve discussed, a positive voltage reading means that this half-cell has a greater tendency to accept electrons, meaning that it will be reduced and can act as an oxidizing agent. In fact, we can compare the standard reduction potential of this half-cell to the standard reduction potential of other half-cells. We can see that a reduction potential of positive 2.87 volts is quite a large reduction potential.
This means that fluorine gas, which is the chemical species on the left-hand side of the equation, is a very strong oxidizing agent compared to other oxidizing agents in other half-cells. So a standard electrode potential of positive 2.87 volts tells us that fluorine gas is a strong oxidizing agent.
