- The Daniell cell was invented in 1836 by a British chemist name John Frederic Daniell.
- It was invented to eliminate the hydrogen bubble problem found in the simple voltaic cell.
- The Daniell cell consist of a zinc electrode and a copper electrode.
- The zinc electrode is immersed in zinc sulphate solution (or sulphuric acid) whereas the copper electrode is immersed in copper(II) sulphate solution.
- Figure below shows the illustration of the Daniell cell.
- Since zinc is more electropositive than copper, hence it acts as the anode and be come the negative therminal of the cell. Copper is the cathode and the positive therminal of the cell.
At Anode (Zinc Electrode)
The zinc atoms release 2 electrons and become zinc ions
The zinc electrode erodes (become thinner).
At Cathode (Copper Electrode)<
The copper(II) ions in the electrolyte are discharged and become zinc atom
The copper electrode become thicker.
- The pointer of the galvanometer deflect.
- The intensity of the blue colour of copper(II) sulphate solution decreases because the concentration of the copper(II) ions deceases.
Function of the Porous Pot:
The function of the porous pot are
- to allow the flow of ions to complete the circuit
- to separate the two electrolytes and hence prevent them from react with each other.
Weaknesses of Daniel Cell
- The electrolyte can easily spill out.
- Difficult to be carried around.
- The voltage produced decreases rapidly owing to the polarity of the cell.