Question

If 21 gram of water is electrolysed, how many moles of H2 gas will be produced.​

Answer 1

Answer:

water (H2O) gives rise to 2 moles of hydrogen gas (H2) at the cathode (-) and one mole of Oxygen gas (O2) at anode (+). Thus, if you want to know what happens if 20 moles of H2O gets electrolytically decomposed then multiply the whole balanced equation with 10 so that now you can see 20 moles of water (2 x 10 moles of H2O) gives 20 moles of H2 gas (2 x 10 moles H2) at the cathode and 10 moles of O2 gas (1 x 10 moles O2) at the anode.

Answer 2

Given:

The mass of water = 21 gm

To Find:

The no of moles of H2 gas produced.​

Calculation:

- The electrolysis of water can be shown as:

2 H2O → 2 H2 + O2

- The no of moles of H2 produced by 36 gm water = 2

⇒ The no of moles of H2 produced by 21 gm water = (2/ 36) × 21

⇒ The no of moles of H2 produced = 1.167

- Hence, 1.167 moles of H2 gas will be produced by electrolysis of 21 gm of water.