Question

How much oxygen will be obtained by the complete electrolysis of $90\text{kg}$ of water?
$2H_{2}O\to 2H_2+O_2$

• A. $80\text{kg}$
• B. $40\text{kg}$
• C. $10\text{kg}$
• D. $90\text{kg}$

Answer 1

The correct option is A $80\text{kg}$

$2H_{2}O\to 2H_2+O_2$

$\text{Number of moles of}{H}_{2}O=\frac{90\times 1000\text{g}}{18}=5000\text{mol}$

2 moles $H_{2}O$ produces 1 mol of $O_2$
So, 5000 mol $H_{2}O$ will produce =$\frac{1}{2}\times 5000=2500\text{mol}$ of $O_2$
Hence, mass of $O_2=2500\times 32=80,000\text{g}$ or $80\text{kg}$