Question

When 8g $H_2$ reacts with 20g of $O_2$ how much water will be formed?

• A. 40g
• B. 43 g
• C. 22.5 g
• D. 72 g

Answer 1

Answer: (C)

22.5 g

The balanced chemical equation for the reaction is given by,

$H_2+\frac{1}{2}{O}_2\to H_{2}O$

From the above equation, $16g$ oxygen will react with $2g$ hydrogen

Hence, $20g$ oxygen will react with $\frac{2}{8}\times 20=2.5g$ hydrogen

Since the amount of hydrogen present is $8g$, oxygen is the limiting reagent and hence it will decide the quantity of product

$16g$ oxygen yields $18g$ water

$20g$ oxygen will yield $\frac{18}{16}\times 20=22.5g$ water

Hence, option $C$ is the correct answer.