name the gas evolved at cathode and anode on electrolysis of water and what is the ratio of the gases evolved?

2016-06-12 12:58 pm

回答 (2)

2016-06-12 1:26 pm
Water dissociates slightly to give hydrogen ions and hydroxide ions.

Hydrogen ions are attracted to the cathode and are then reduced to hydrogen gas.
2H⁺(aq) + 2e⁻ → H₂(g)

On the other hand, hydroxide ions are attracted to the anode and are then oxidized to oxygen gas.
4OH⁻(aq) → 2H₂O(l) + O₂(g) + 4e⁻

The equation of the overall reaction is :
2H₂O(l) → 2H₂(g) + O₂(g)
According to the equation, mole ratio and volume ratio H₂ : O₂ = 2 : 1

Conclusively, hydrogen gas is evolved at the cathode while oxygen gas at the anode. The mole ratio and volume ratio of hydrogen gas to oxygen gas are 2 : 1.
2016-06-12 1:23 pm
During electrolysis: 2H2O --> O2 (g) + 2H2 (g)
O2 is formed at the positive electrode
H2 is formed at the negative electrode
The ratio would be 1 molecule of O2 to every 2 molecules of H2 (1:2) becuase of the equation at the top - you get 1 mole of oxygen for every 2 moles of hydrogen


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