Question

$28$ ml of nitrogen are reacted with $15$ ml of hydrogen. How many millilitres of which gas are left unreacted?

• A. $5$ ml $H_2$
• B. $5$ ml $N_2$
• C. $7$ ml $H_2$
• D. $11$ ml $N_2$
• E. $23$ ml $N_2$

Answer 1

The correct option is E $23$ ml $N_2$

Nitrogen reacts with hydrogen to produce ammonia.
$N_2+3H_2\to 2N{H}_3$
Thus 1 mole of nitrogen reacts with 3 moles of hydrogen.
Volume is directly proportional to number of moles.
Thus 1 ml of nitrogen reacts with 3 ml of hydrogen.
Hence, 15 ml of hydrogen will react with $15\times \frac{1}{3}=5$ ml of nitrogen.
$28-5=23$ ml of nitrogen are left unreacted.