Sketch the galvanic cells based on the following half-reactions. Show the direction of electron flow, show the direction of ion migration through the salt bridge, and identify the cathode and anode. Give the overall balanced equation, and determine for the galvanic cells. Assume that all concentrations are 1.0 M and that all partial pressures are 1.0 atm. a. b.

Interpretation:

The reaction taking place in two different galvanic cell is given. The sketch of the given galvanic cell along with the cathode and anode and the direction of electron flow, direction of flow of migration of ions through salt bridge, the balanced chemical equation and calculation of E° is to be stated.

Concept introduction:

The galvanic cell converts chemical energy into electrical energy while the electrolytic cell converts electrical energy into chemical energy.

The species at anode undergoes oxidation while the species at cathode undergoes reduction and the electrons generated at the anode are transferred through wire to the cathode.

The galvanic cell based on the given reaction is represented by the following sketch.

The anode compartment consists of platinum electrode present in contact with 1.0 M Cl− ions in electrolytic solution through which chlorine gas is bubbled while the cathode compartment consists of platinum electrode present in contact with 1.0 M Br− ions in the solution through which bromine gas is bubbled.

Figure 1

The electrons flow from the anode compartment having platinum electrode in contact with Br− to the cathode compartment having platinum electrode in contact with Cl− . The cations flow towards cathode while anions flow towards anode via salt bridge.

The species at anode undergoes oxidation while the species at cathode undergoes reduction reaction. Therefore, the electrons generated at cathode travel to cathode through wire in an electrical circuit. Inside the solution the flow of ions occur so as to maintain the overall charge of the reaction.

The overall balanced chemical equation for given reaction (a) is,

Cl2(g)+2Br−(aq)→2Cl−(aq)+Br2(g)

As the value of reduction potential of chlorine is more than the bromine. Therefore, chlorine will undergo reduction reaction while bromine will undergo oxidation reaction.

The value of E°cell is calculated as 0.27 V_ .

The reaction taking place at cathode is,

Cl2(g)+2e−→2Cl−(aq)   E°red=+1

Interpretation:

The reaction taking place in two different galvanic cell is given. The sketch of the given galvanic cell along with the cathode and anode and the direction of electron flow, direction of flow of migration of ions through salt bridge, the balanced chemical equation and calculation of E° is to be stated.

Concept introduction:

The galvanic cell converts chemical energy into electrical energy while the electrolytic cell converts electrical energy into chemical energy.

The species at anode undergoes oxidation while the species at cathode undergoes reduction and the electrons generated at the anode are transferred through wire to the cathode.