Daniell Cell Working:
In1836, a British chemist and meteorologist John Frederic Daniell invented an electrochemical cell named as Daniell cell. John Frederic Daniell wants to find a way to get rid from the hydrogen bubble problem which was occurred at the time of the voltaic pile.For its solution to consume the hydrogen produced by the first, he decided to use a second electrolyte. In this cell, a copper pot is filled with a copper sulfate solution, an unglazed earthenware container that is filled with sulfuric acid and a zinc electrode is also immersed in it.
Now adays, the technologies which are used in the early days of battery development are improved by Daniell cell. A Frenchman named Callaud invented a modified cell of Daniell cell that is known as gravity cell or crowfoot cell. In a Daniell cell there are two half-cells. In the first half-cell, zinc rod dipped in 1M solutions and in the other one copper rod dipped in a 1M solutions. To separate both half cells from each other, a salt bridge is used.
Elements of a Daniell cell:
The Daniell cell is constructed through the combination of different chemical and non-chemical materials which are given below:- A large beaker, bowl or other suitable container
- A plastic tube
- A porous vase (as discussed in the introduction)
- A strip of copper
- A strip of zinc
- A voltmeter
- Copper sulfate (cuso4)
- Cotton
- Distilled water
- Potassium nitrate (kno3)
- Sodium chloride (nacl) if potassium nitrate is unavailable
- Two cables with alligator clips
- Zinc sulfate (znso4)
Working of Daniell Cell:
To represent the competition between two different kinds of metal atoms for electrons, the half reactions can be used. Zinc atoms become more reactive and more electrons are loosed in such cases as compare to copper. Simultaneously, both reactions take place on both half cells. Through the wire from the zinc anode to the copper cathode in the external circuit, electrons are traveled in this cell. The bulb, which is available in the circuit, will light up. If a voltmeter is available, their voltage can be checked out. To complete the circuit, both the positive and negative ions move through the aqueous solutions via the salt bridge.Working formula:
At the anode:Oxidation ---------------- loss of electrons.
Zn_{(s)}\rightarrow Zn^{2+}_{(aq)}+2e^-
At cathode:
Reduction -------------gain of electrons.
Cu^{2+}_{(aq)}+2e^{-} \rightarrow Cu _{(s)}
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