Consider the standard galvanic cell based on the following half-reactions: Cu 2 + + 2 e − → Cu Ag + + e − → Ag The electrodes in this cell are Ag( s ) and Cu( s ). Does the cell potential increase. decrease. or remain the same when the following changes occur to the standard cell? a. CuSO 4 ( s ) is added to the copper half-cell compartment (assume no volume change). b. NH 3 ( aq ) is added to the copper half-cell compartment ( Hint : Cu 2+ reacts with NH 3 , to form Cu(NH 3 ) 4 2+ ( aq ).] c. NaCl( s ) is added to the silver half .cell compartment ( Hint : Ag + reacts with Cl − to form AgCl( s ).] d. Water is added to both half-cell compartments until the volume or solution is doubled. e. The silver electrode is replaced with a platinum electrode

Interpretation:

A galvanic cell having Silver and Copper electrodes is given. The change in the standard cell when any change is carried out in any compartment for the given reactions is to be stated.

Concept introduction:

The relationship between reduction potential and standard reduction potential value and activities of species present in an electrochemical cell at a given temperature is given by the Nernst equation.

The value of Ecell is calculated using Nernst formula,

E=E°−(RTnF)ln(Q)

At room temperature, the above equation is specified as,

E=E°−(0.0591n)log(Q)

This relation is further used to determine the relation between ΔG° and K , ΔG° and E°cell .

To determine: The change in the standard cell when CuSO4(s) is added to the Copper half-cell compartment.

When CuSO4(s) is added to the Copper half-cell compartment, the value of Ecell decreases.

Given,

The reactions taking place in the cell are,

Cu2++2e−→CuAg++e−→Ag

On the basis of reduction potential values, the reaction taking place at each electrode is given as,

The reaction taking place at the cathode is,

Ag++e−→Ag   E°red=0.80 V

The reaction taking place at the anode is,

Cu→Cu2++2e−   E°=−0.34 V

Multiply the reduction half-reaction with a coefficient of 2 and then add both the oxidation and reduction half-reaction.

2Ag++2e−→2AgCu→Cu2++2e−

The final equation is,

Cu+2Ag+→Cu2++2Ag

The value of E°cell is given as,

E°cell=E°ox+E°red=−0

Interpretation:

A galvanic cell having Silver and Copper electrodes is given. The change in the standard cell when any change is carried out in any compartment for the given reactions is to be stated.

Concept introduction:

The relationship between reduction potential and standard reduction potential value and activities of species present in an electrochemical cell at a given temperature is given by the Nernst equation.

The value of Ecell is calculated using Nernst formula,

E=E°−(RTnF)ln(Q)

At room temperature, the above equation is specified as,

E=E°−(0.0591n)log(Q)

This relation is further used to determine the relation between ΔG° and K , ΔG° and E°cell .

To determine: The change in the standard cell when NH3(aq) is added to the Copper half-cell compartment.

When NH3(aq) is added to the Copper half-cell compartment, the value of Ecell increases.

Interpretation:

A galvanic cell having Silver and Copper electrodes is given. The change in the standard cell when any change is carried out in any compartment for the given reactions is to be stated.

Concept introduction:

The relationship between reduction potential and standard reduction potential value and activities of species present in an electrochemical cell at a given temperature is given by the Nernst equation.

The value of Ecell is calculated using Nernst formula,

E=E°−(RTnF)ln(Q)

At room temperature, the above equation is specified as,

E=E°−(0.0591n)log(Q)

This relation is further used to determine the relation between ΔG° and K , ΔG° and E°cell .

To determine: The change in the standard cell when NaCl(s) is added to the Silver half-cell compartment.

When NaCl(s) is added to the Silver half-cell compartment, the value of Ecell decreases.

Interpretation:

A galvanic cell having Silver and Copper electrodes is given. The change in the standard cell when any change is carried out in any compartment for the given reactions is to be stated.

Concept introduction:

The relationship between reduction potential and standard reduction potential value and activities of species present in an electrochemical cell at a given temperature is given by the Nernst equation.

The value of Ecell is calculated using Nernst formula,

E=E°−(RTnF)ln(Q)

At room temperature, the above equation is specified as,

E=E°−(0.0591n)log(Q)

This relation is further used to determine the relation between ΔG° and K , ΔG° and E°cell .

To determine: The change in the standard cell when water is added to both half-cell compartments until the volume of solution is doubled.

When water is added to the both the half-cells, there occurs a decrease in the value of Ecell .

Interpretation:

A galvanic cell having Silver and Copper electrodes is given. The change in the standard cell when any change is carried out in any compartment for the given reactions is to be stated.

Concept introduction:

The relationship between reduction potential and standard reduction potential value and activities of species present in an electrochemical cell at a given temperature is given by the Nernst equation.

The value of Ecell is calculated using Nernst formula,

E=E°−(RTnF)ln(Q)

At room temperature, the above equation is specified as,

E=E°−(0.0591n)log(Q)

This relation is further used to determine the relation between ΔG° and K , ΔG° and E°cell .

To determine: The change in the standard cell when Silver electrode is replaced with Platinum electrode.

Step: 5

The value of Ecell will remain same when Silver electrode is replaced with Platinum electrode.