Which method can be used to determine the strength of a reductant or oxidant in a solution? Explain with an example.
(N/A) The strength of a reductant or oxidant can be determined by measuring the standard electrode potential $(E^{\circ})$ of the half-cell by connecting it with a Standard Hydrogen Electrode $(SHE)$.
$1$. Construct an electrochemical cell by connecting the half-cell of interest with a $SHE$ (where $E^{\circ}_{SHE} = 0.00 \ V$).
$2$. Measure the standard cell potential $(E^{\circ}_{cell})$.
$3$. Using the formula $E^{\circ}_{cell} = E^{\circ}_{cathode} - E^{\circ}_{anode}$,calculate the standard electrode potential of the half-cell.
$4$. $A$ more negative $E^{\circ}$ value indicates a stronger reducing agent,while a more positive $E^{\circ}$ value indicates a stronger oxidizing agent.
Example: Determining the standard electrode potential of $Zn^{2+}/Zn$.
When $Zn$ electrode is connected to $SHE$ as an anode,the measured $E^{\circ}_{cell} = 0.76 \ V$.
$E^{\circ}_{cell} = E^{\circ}_{cathode} - E^{\circ}_{anode}$
$0.76 \ V = 0.00 \ V - E^{\circ}_{Zn^{2+}/Zn}$
$E^{\circ}_{Zn^{2+}/Zn} = -0.76 \ V$
Since the value is negative,$Zn$ acts as a strong reducing agent.
$1$. Construct an electrochemical cell by connecting the half-cell of interest with a $SHE$ (where $E^{\circ}_{SHE} = 0.00 \ V$).
$2$. Measure the standard cell potential $(E^{\circ}_{cell})$.
$3$. Using the formula $E^{\circ}_{cell} = E^{\circ}_{cathode} - E^{\circ}_{anode}$,calculate the standard electrode potential of the half-cell.
$4$. $A$ more negative $E^{\circ}$ value indicates a stronger reducing agent,while a more positive $E^{\circ}$ value indicates a stronger oxidizing agent.
Example: Determining the standard electrode potential of $Zn^{2+}/Zn$.
When $Zn$ electrode is connected to $SHE$ as an anode,the measured $E^{\circ}_{cell} = 0.76 \ V$.
$E^{\circ}_{cell} = E^{\circ}_{cathode} - E^{\circ}_{anode}$
$0.76 \ V = 0.00 \ V - E^{\circ}_{Zn^{2+}/Zn}$
$E^{\circ}_{Zn^{2+}/Zn} = -0.76 \ V$
Since the value is negative,$Zn$ acts as a strong reducing agent.
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