What are galvanic cells and explain its working?, Chemistry

The device through which chemical energy is converted into electrical energy is known as galvanic cell or electrochemical cell or voltaic cell. In a galvanic cell, a redox reaction is carried out in an indirect manner and the decrease in free energy process appears as electrical energy. An indirect redox reaction is such that reduction and oxidation processes are carried in separate vessels. In order to understand this phenomenon, let us consider the Zn - CuSO4 reaction as the basis of the cell reaction.

In its simple form, a zinc strip is dipped in the ZnSO4 solution and copper strip is dipped in the CuSO4 solution taken in separate beakers. The two metallic strips which act as electrodes are connected by the stripes conducting wires through a voltmeter. The two solutions are connected through a reversed U-tube known as salt bridge. The U-tube is filled with the solution of some electrolyte such KCl, KNO3 or NH4Cl to which gelatin or agar-agar has been added to convert it into semi-solid paste. A schematic of this cell has been shown.

The deflection in voltmeter shows that there is a potential difference between the two electrodes. It has been establish that the conventional current flows from the outer circuit from copper to zinc strip. It means that the electrons flow occurs from zinc to copper strip.

Let us now understand the working of the cell.

(i) Zinc undergoes oxidization to form zinc ions

Zn(s)  258_halides.png  Zn2+(aq) + 2e- (oxidization)

(ii) The electrons liberated during oxidization are pushed through the connecting wires to copper strip.

(iii) Copper ions move towards copper strip, pick up the electrons, and get reduced to copper atoms which hare deposited at the copper strip.

(iv) Cu2+(aq) + 2e-  258_halides.png  Cu(s) (reduction)

The electrode at which oxidization occurs is anode and that at which reduction occurs is cathode. In the above that, zinc strip is anode and the copper strip is cathode. Due to the oxidization process occurring at the anode it becomes a source of electrons and acquires a negative charge in the cell. Similarly, due to the reduction process occurring at the cathode it acquires positive charge and becomes a receiver of the electrons. Thus the electrochemical cell, anode electrode acts as negative terminal and cathode electrode acts as a positive terminal.




Posted Date: 6/26/2012 1:24:14 AM | Location : United States

Related Discussions:- What are galvanic cells and explain its working?, Assignment Help, Ask Question on What are galvanic cells and explain its working?, Get Answer, Expert's Help, What are galvanic cells and explain its working? Discussions

Write discussion on What are galvanic cells and explain its working?
Your posts are moderated
Related Questions
GEOCHEMISTRY The chemical processes taking place in the crust are especially important as they have build ores, concentrated mineral deposits that are exploited industrially

In polar covalent molecule, one atom gets positive charge and the other one takes negative charge as known as dipole.

DIFFRACTION BY SOLIDS Diffraction performs when a wave interacts with a lattice whose dimensions are of the same order of magnitude as that of the wavelength of the waves. The

The quantum number 'm' of a free gaseous atom is associated with : (1) The effective volume of the orbital (2) The shape of the orbital (3) The spatial orientation of the

Q. Show the Occurrence of the f-block element? Apart from promethium which is unstable and is found in traces in uranium ores, all the lanthanides usually occur together. Altho

Equilibrium constants A complex in general is any species build by specific association of molecules or ions by donor-acceptor interactions. In aqueous solutions the most import

The intramolecular product tetrahydrofuran results from an internal nucleophilic substitution reaction of the alkoxide on the alkyl halide. The intermolecular product 1,4-butanedio

General Tests of Esters (a) Esters has sweet smell (b)  Esters is neutral towards litmus (c) A pink colour is developed while one or two drops of phenolphthalein are adde

notes on emde degradation