Question

If 9g of H₂O is electrolysed completely with 50% current efficiency, then how much O2 will be formed at STP?

Answer 1

Ans;

Number of moles of water in the given weight (n) = given weight/molecular weight
= 9/18
= 0.5

Balanced Equation for the electrolysis of water

2 H2O →2 H2 + O2

From the equation it is confirmed that 2 moles of water dissociates to produce 1 mole of water at STP.

But for the given 0.5 moles of water will produce only 0.25moles of Oxygen at STP.

At STP 1 mole of Oxygen will occupy 22.4 liters of Oxygen or 32 g of oxygen.

Then 0.25 moles of Oxygen = (0.25 *32)
=8 g of oxygen.
Or
volume=22.4*1/4=5.6 L at STP

is the answer.

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