What is SCE potential?
The saturated calomel electrode (SCE) is a reference electrode based on the reaction between elemental mercury and mercury(I) chloride. The electrode is normally linked via a porous frit to the solution in which the other electrode is immersed. This porous frit is a salt bridge.
What is the electrode potential of calomel electrode?
The reference potential of SCE is 0.241 V(at 25°C) , because of increased activity of chloride ion in internal solution of saturated KCl (ca. 4.8 M). In addition to the chloride concentration dependence of potential, the temperature dependence of potential is about -0.5 mV per degree.
Why is KCl used in SCE?
It is composed of a solid paste of Hg2Cl2 and liquid elemental mercury attached to a rod that is immersed in a saturated KCl solution. It is necessary to have the solution saturated because this allows for the activity to be fixed by the potassium chloride and the voltage to be lower and closer to the SHE.
What is electrode potential with diagram?
In electrochemistry, electrode potential is the electromotive force of a galvanic cell built from a standard reference electrode and another electrode to be characterized. By convention, the reference electrode is the standard hydrogen electrode (SHE). It is defined to have a potential of zero volts.
What are advantages of SCE?
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How is electrode potential measured?
The standard electrode potential is measured by the potentiometer. It is the potential difference when no current is flowing in the circuit.
What is electrode potential of standard hydrogen electrode?
Its absolute electrode potential is estimated to be 4.44 ± 0.02 V at 25 °C, but to form a basis for comparison with all other electroreactions, hydrogen’s standard electrode potential (E°) is declared to be zero volts at any temperature.
What are the two main chemicals used in calomel electrode?
A saturated water solution of KCl (potassium chloride) is in contact with the mercury and the mercury(I) chloride (also known as “calomel”). Linking the electrode to the solution in which the other electrode is immersed is a porous frit, which is a salt bridge.
What is the formula of electrode potential?
Write the equation for the half-reaction that occurs at the anode along with the value of the standard electrode potential for the half-reaction. Use Equation 6.2….Calculating Standard Cell Potentials.
| Half-Reaction | E° (V) |
|---|---|
| 2H+(aq) + 2e− ⇌ H2(g) | 0.00 |
| Sn4+(aq) + 2e− ⇌ Sn2+(aq) | 0.154 |
| Cu2+(aq) + e− ⇌ Cu+(aq) | 0.159 |
How is the SCE electrode used in electrochemistry?
The SCE is used in pH measurement, cyclic voltammetry and general aqueous electrochemistry. This electrode and the silver/silver chloride reference electrode work in the same way. In both electrodes, the activity of the metal ion is fixed by the solubility of the metal salt.
What are the values of the standard electrode potential?
The data values of standard electrode potentials are given in the table below, in volts relative to the standard hydrogen electrode, and are for the following conditions: A temperature of 298.15 K (25.00 °C; 77.00 °F).
What is the potential of a saturated calomel electrode?
The standard potential for this reaction is +0.268 V. If the cell is saturated with KCl at 25°C, the potential is +0.241 V. A calomel electrode saturated with KCl is called a saturated calomel electrode, abbreviated S.C.E. (and pictured to the right). The advantage in using saturated KCl is that [Cl−] does not change if some liquid evaporates.
Which is the only variable in the SCE potential?
SCE potential. The only variable in this equation is the activity (or concentration) of the chloride anion. But since the inner solution is saturated with potassium chloride, this activity is fixed by the solubility of potassium chloride, which is: 342 g/L74.5513 g/mol = 4.587 M @ 20 °C.
