Galvanic Cell

A galvanic cell is a device that converts chemical energy into electrical energy by using a spontaneous oxidation-reduction process. Galvanic cells utilise the electrical energy released by electron transport in a redox reaction to do beneficial electrical work. Luigi Galvani found in 1780 that when two distinct metals (e.g., copper and zinc) are in contact and then both are contacted at the same time to two separate regions of a muscle in a frog leg, the frog’s leg contracts to shut the circuit. A galvanic cell, in essence, is used to transform the chemical energy held in ions into electrical energy in the form of current. A battery, for example, is a package of one or more galvanic cells used for the chemical generation and storage of electric energy. Galvanic cells are also useful for corrosion prevention. A galvanic cell may be made from any two metals. When two metals come into contact, one can operate as an anode and the other as a cathode, resulting in galvanic corrosion of the more anodic metal.

WORKING OF GALVANIC CELL

A galvanic cell operates in a straightforward manner. It entails a chemical process that produces electric energy as a byproduct. During a redox reaction, a galvanic cell uses electron energy transfer to turn chemical energy into electric energy.

The ability of a galvanic cell to split the flow of electrons in the process of oxidation and reduction by creating a half reaction and connecting each with a wire so that a channel for the flow of electrons via such wire may be constructed is used. This movement of electrons is referred to as a current. A current of this type may be produced to flow via a wire in order to complete a circuit and acquire its output in any device, such as a television or a watch.

SETUP OF A GALVANIC CELL

To construct a galvanic cell, the following steps must be taken. Ideally, the cell would have two electrodes. One of these electrodes, the cathode, must be positively charged, while the other, the anode, must be negatively charged.

These two electrodes will be the galvanic cell’s two key components. The reduction half-reaction will take place at the cathode, while the oxidation half-reaction will take place at the anode. As previously stated, any two metals can be utilised to initiate the chemical reaction.

UNDERSTANDING THE GALVANIC CELL WITH AN EXAMPLE

Let’s say the two metals involved in the chemical reaction are zinc and copper. Zinc would lose two electrons as a result of the chemical process. This will be absorbed by copper and transformed into elemental copper. Because these two metals will be put in separate containers and connected by a conducting wire, an electric current will be produced, transferring all electrons from one metal to the other.

       Simultaneously, the two metals must be submerged in a salt solution, such as zinc sulphate and copper sulphate in this example. In this situation, the two solutions are not directly mixed together, but can be linked by a bridge or a medium. This medium will be responsible for the transport of ions while also ensuring that the two solutions do not combine. 

    This bridge assists in completing the circuit for conveying the electric charge and also ensures that the solutions in the metal-containing containers stay neutral and do not mix. It makes no difference whether salt bridge is utilised in the chemical process as long as it does not interfere with the redox reaction, which occurs during oxidation and reduction.

GALVANIC CORROSION

The electrochemical deterioration of metals is known as galvanic corrosion. When two different metals come into touch with each other in the presence of an electrolyte, such as salt water, corrosion occurs. This results in the formation of a galvanic cell, with hydrogen gas developing on the more noble (less active) metal. The electrochemical potential generated then generates an electric current, which electrolytically dissolves the less noble element. When the same metal is exposed to two distinct electrolyte concentrations, a concentration cell is generated.

SOME IMPORTANT TERMS

The following are some of the significant terminology used in galvanic cells:

Electrode- It refers to the two metals that serve as the cathode and anode.

The connecting bridge or medium that permits a redox reaction to occur is known as a salt bridge.

The chemical processes that allow an electric current to generate and flow through a galvanic cell are referred to as oxidation and reduction.

SOLVED EXAMPLE

What happens in a galvanic cell if no salt bridge is employed while the redox reaction is taking place?

Solution: In the absence of a salt bridge within each container containing the metals, the redox reaction would begin in much the same way. But in the absence of the salt bridge, the same would come to an end rather abruptly. The respective solutions will not be able to maintain their electric neutrality. Other than this, there will be no change in the chemical reaction or any alteration of any type because of the absence of the salt bridge or medium.

CONCLUSION

Therefore we can conclude from this whole article that Electrochemistry is a discipline of chemistry concerned with the interactions of chemical and electrical energy in a solution at the interface of the conductors, ionic conductor and electric conductor. A voltaic cell is made up of two half cells, with one half cell’s electrode made of metal A and the other half cell’s electrode made of metal B. To create power, a Zinc – Copper Voltaic Cell is employed. It is made up of two independent half cells that are made up of an electrode, a strip of metal within a solution. A wire connects the half cells, Zinc and Copper, by flowing from one electrode to the other. To link the two half cells, we utilise a salt bridge, which is constructed by filling a U-shaped tube with saline solution.