Question

During the electrolysis of water 4 mol of electrons were transferred from anode to cathode. the total volume of gases produced at STP will be approximately

Answer 1

Electrolysis of water

This is the decomposition of water (H2O) into oxygen (O2) and hydrogen gas (H2) when an electric current is passed through the water. Usually some salt/acid is added to the water to make this process possible.


The chemical equation for the reaction is:

2 H2O(l) → 2 H2(g) + O2(g)



The half equations/reactions at anode and cathode:

Anode: 2 H2O(l) = O2(g) + 4 H+(aq) + 4e−  


Cathode: 2 H+(aq) + 2e− = H2(g)



From the half equations, 4 moles of electrons will give 1 mole of O2 and 2 moles of H2.



Total number of moles of gases = 1 + 2 =  3 moles


Molar gas volume at STP = 22.4 litres



Total volume of gases =  3 x 22.4 

                                    = 67.2 litres

Answer 2

Answer:

Explanation:

During electrolysis the reaction occurs as:

H2O ---> H2 + 1/2O2

1mol ......... 1mol... 0.5 mol

So, we see that,

1 mole water releases = 1 mole H2 gas = 22.4 L H2 gas

Since, 1 mole of water requires = 2moles of electrons

So, 2 moles of electrons produces = 22.4 L H2 gas

Hence, 4 moles of electrons will produce = (22.4/2) x 4 = 44.8 L H2 gas

Similarly, 4 moles of electrons will produce = (11.2/2) x 4 = 22.4 L O2 gas

Hence, total volume of gases at STP = 44.8+ 22.4 = 67.2 L