Question

$40$ ml of ammonia gas was taken in a eudiometer tube and subjected to sparks till the volume did not further change. The volume was found to increase by $40$ ml. $40$ ml of oxygen gas then mixed and the mixture was further exploded. The gases remaining were $30$ ml. Deduce the formula of ammonia. (Ammonia contains $N$ and $H$ only)

Answer 1

Let he formula be $N_x{H}_y$

$N_x{H}_y\to \frac{x}{2}{N}_2+\frac{y}{2}{H}_2$

The equation is,

$\frac{x}{2}\times 40+\frac{y}{2}\times 40=80$

$x+y=4-----\left(1\right)$

Now $N_2$ is left and $H_2$ reacts with $O_2$ to form water

$H_2+\frac{1}{2}{O}_2\to H_{2}0$

$\frac{x}{2}\times 40+40-10y=30$

Since volume left will be the combination of $N_2$ and $O_2$ left

$2x-y=-1----\left(2\right)$

Solving 1 and 2 we get

$x=1$

$y=3$

Thus the formula is $N{H}_3$