Question
Explain about SHE (Standard Hydrogen Electrode).
✓
Answer
1. It is impossible to measure the emf of a single electrode, but we can $H _2$ out $H _2$ measure the potential difference between two electrodes ( $E_{\text {cell }}$ ) using a voltmeter.
2. To calculate the emf of a single electrode, we need a reference electrode whose emf is known. For that purpose, Standard Hydrogen
Electrode (SHE) is used as the reference electrode.
3. SHE has been assigned an orbitary emf of exactly zero volt.
4. It consists of platinum electrode in contact with $1 MHC1$ solution and 1 atm hydrogen gas.
5. The hydrogen gas bubbled through the solution at $25^{\circ} C$. SHE can act as cathode as well as an anode.
6. The Half cell reactions are given below:
If SHE is used as a cathode, the reduction reaction is
$2 H^2+2 e^{-}+H_{2(g, 1 atm)} E^{\circ}=0 \text { volt }$
If SHE is used as an anode, the oxidation reaction is
$H_{2(g, 1 atm)} 2 H^{+}{ }_{(aq, 1 M)}+2 e^{-} E^{\circ}=0 \text { volt. }$
2. To calculate the emf of a single electrode, we need a reference electrode whose emf is known. For that purpose, Standard Hydrogen
Electrode (SHE) is used as the reference electrode.
3. SHE has been assigned an orbitary emf of exactly zero volt.
4. It consists of platinum electrode in contact with $1 MHC1$ solution and 1 atm hydrogen gas.
5. The hydrogen gas bubbled through the solution at $25^{\circ} C$. SHE can act as cathode as well as an anode.
6. The Half cell reactions are given below:
If SHE is used as a cathode, the reduction reaction is
$2 H^2+2 e^{-}+H_{2(g, 1 atm)} E^{\circ}=0 \text { volt }$
If SHE is used as an anode, the oxidation reaction is
$H_{2(g, 1 atm)} 2 H^{+}{ }_{(aq, 1 M)}+2 e^{-} E^{\circ}=0 \text { volt. }$
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