Question

What happens when electricity is passed through acidified water? What type of reaction is it? Write the chemical equation.

Answer 1

Hint: Electricity can pass through substances that show mobility of charged species. Pure water cannot dissociate into its ions and show movement of ions, therefore it does not conduct electricity. Acidification of water is performed to make water a good conductor of electricity.

Complete answer:
Different chemical reactions can be classified into various categories depending upon the type of reactants and products involved, the reagents used and the type of chemical changes observed during the reaction.
Acidification of water is the process of introducing hydrogen ions into pure water. The presence of free ions that can move through the medium makes the acidified water a good conductor of electricity. The two electrodes of a cell are immersed into the acidified water and the current is allowed to run through the circuit.
The effect of electric current is such that the positively charged hydrogen ions migrate towards the negative electrode called the cathode and the negatively charged oxide ions migrate towards the positively charged electrode called the anode. This movement of ions towards the electrodes of opposite polarity is known as electrolysis and it results in the liberation of hydrogen gas at cathode and oxygen gas at anode.
Thus, passing electricity through acidified water results in an electrolytic decomposition reaction of water. The products of the reaction are hydrogen gas and oxygen gas. The chemical reaction can be written as follows:
\[2{H_2}O(l)\xrightarrow{{{\text{electrolytic decomposition}}}}2{H_2}(g) + {O_2}(g)\]

Note:
No two electrodes in a cell carry a permanent charge or have a fixed polarity. The sign of the electrode depends upon the type of cell that it is a part of. Electrolytic cells have a negative cathode and a positive anode however galvanic cells have the opposite polarity.