Question

What is the number of moles of oxygen gas evolved by electrolysis of $180g$ of water?

• A. $2.5$
• B. $5.0$
• C. $7.5$
• D. $10.0$

Answer 1

Answer: (B)

$5.0$

$2H_{2}O\left(l\right)\to 2H_2\left(g\right)+O_2\left(g\right)$

moles of water=$\frac{180}{18}=10$

1 mole of oxygen for 2 moles of water.

So, 5 moles of oxygen for 10 moles of water.