The saturated calomel electrode. abbreviated SCE. is often used as a reference electrode in making electrochemica1 measurements. The SCE is composed of mercury in contact with a saturated solution of calomel (Hg 2 Cl 2 ). The electrolyte solution is saturated KCI. is +0.242 V relative to the standard hydrogen electrode. Calculate the potential for each of the following galvanic cells containing a saturated calomel electrode and the given half-cell components at standard conditions. In each case. indicate whether the SCE is the cathode or the anode. Standard reduction potentials are found in Table 17.1. a. Cu 2+ + 2 e − → Cu b. Fe 3 + + e - → Fe 2 + c. AgCl + e - → Ag + Cl - d. Al 3 + + 3 e − → Al e. Ni 2 + + 2 e − → Ni

Interpretation:

The use of saturated Calomel electrode (SCE) as a reference electrode in making of electrochemical measurements and its formation by combination of Mercury and saturated solution of calomel (Hg2Cl2) , which is present in contact with an electrolytic solution of saturated KCl is given. The potential for the given galvanic cells containing calomel electrode and the given half-cell and the cathodic or anodic nature of SCE has to be calculated.

Concept introduction:

An electrode that is highly stable and whose electrode potential value is known is called reference electrode. The reference electrode is used for the construction of an electrochemical cell.

To determine: The potential for the given galvanic cell containing calomel electrode and the given half-cell components and the cathodic or anodic nature of SCE.

As the reduction potential of Copper is greater than the standard calomel electrode, therefore the standard calomel electrode acts as the anode, while the Copper electrode acts as the cathode.

The potential for the given galvanic cell containing calomel electrode and the given half-cell components is 0.098 V_ .

Given,

The value of ESCE is +0.242 V .

The value of standard reduction potential for the given half-reaction is,

Cu2++2e−→Cu   E°=0.34 V

As the reduction potential of Copper is greater than the standard calomel electrode, therefore the standard calomel electrode acts as the anode, while the Copper electrode acts as the cathode.

The reaction taking place at the cathode is,

Cu2++2e−→Cu   E°red=0.34 V

The reaction taking place at the anode is,

2Hg+2Cl−→Hg2Cl2+2e−   E°ox=−0.242 V

The value of E°cell is given as,

E°cell=E°ox+E°red

Where,

• E°ox is the oxidation potential of anode

Interpretation:

The use of saturated Calomel electrode (SCE) as a reference electrode in making of electrochemical measurements and its formation by combination of Mercury and saturated solution of calomel (Hg2Cl2) , which is present in contact with an electrolytic solution of saturated KCl is given. The potential for the given galvanic cells containing calomel electrode and the given half-cell and the cathodic or anodic nature of SCE has to be calculated.

Concept introduction:

An electrode that is highly stable and whose electrode potential value is known is called reference electrode. The reference electrode is used for the construction of an electrochemical cell.

To determine: The potential for the given galvanic cells containing calomel electrode and the given half-cell components and the cathodic or anodic nature of SCE.

As the reduction potential of Iron is greater than the standard calomel electrode, therefore the standard calomel electrode acts as the anode, while the Iron electrode acts as the cathode.

The potential for the given galvanic cell containing calomel electrode and the given half-cell components is 0.528 V_ .

Interpretation:

The use of saturated Calomel electrode (SCE) as a reference electrode in making of electrochemical measurements and its formation by combination of Mercury and saturated solution of calomel (Hg2Cl2) , which is present in contact with an electrolytic solution of saturated KCl is given. The potential for the given galvanic cells containing calomel electrode and the given half-cell and the cathodic or anodic nature of SCE has to be calculated.

Concept introduction:

An electrode that is highly stable and whose electrode potential value is known is called reference electrode. The reference electrode is used for the construction of an electrochemical cell.

To determine: The potential for the given galvanic cell containing calomel electrode and the given half-cell and the cathodic or anodic nature of SCE.

As the reduction potential of AgCl is lower than the standard calomel electrode, therefore the standard calomel electrode acts as the cathode, while the AgCl electrode acts as the anode.

The potential for the given galvanic cell containing calomel electrode and the given half-cell components is 0.022 V_ .

Interpretation:

The use of saturated Calomel electrode (SCE) as a reference electrode in making of electrochemical measurements and its formation by combination of Mercury and saturated solution of calomel (Hg2Cl2) , which is present in contact with an electrolytic solution of saturated KCl is given. The potential for the given galvanic cells containing calomel electrode and the given half-cell and the cathodic or anodic nature of SCE has to be calculated.

Concept introduction:

An electrode that is highly stable and whose electrode potential value is known is called reference electrode. The reference electrode is used for the construction of an electrochemical cell.

To determine: The potential for the given galvanic cell containing calomel electrode and the given half-cell components and the cathodic or anodic nature of SCE.

As the reduction potential of Aluminum is lower than the standard calomel electrode, therefore the standard calomel electrode acts as the cathode, while the Aluminum electrode acts as the anode.

The potential for the given galvanic cell containing calomel electrode and the given half-cell components is 1.902 V_ .

Interpretation:

The use of saturated Calomel electrode (SCE) as a reference electrode in making of electrochemical measurements and its formation by combination of Mercury and saturated solution of calomel (Hg2Cl2) , which is present in contact with an electrolytic solution of saturated KCl is given. The potential for the given galvanic cells containing calomel electrode and the given half-cell and the cathodic or anodic nature of SCE has to be calculated.

Concept introduction:

An electrode that is highly stable and whose electrode potential value is known is called reference electrode. The reference electrode is used for the construction of an electrochemical cell.

To determine: The potential for the given galvanic cell containing calomel electrode and the given half-cell components and the cathodic or anodic nature of SCE.

As the reduction potential of Nickel is lower than the standard calomel electrode, therefore the standard calomel electrode acts as the cathode, while the Nickel electrode acts as the anode.

The potential for the given galvanic cell containing calomel electrode and the given half-cell components is 0.472 V_ .