Question

Illustrate the law of reciprocal proportions from the following results:

(a) In phophorus chloride, $P =22.57 \%, Cl =77.43 \%$

(b) In phosphinc, $P =91.18 \%, H =8.82 \%$

(c) In hydrogen chloride, $H =2.77 \%, Cl =97.23 \%$

Answer 1

SOLTUION : (a) In phosphorus chloride, $22.57$ gram of P combines with $77.43$ gram of chlorine.

(b) In phosphine, $91.18 g$ of $P$ combines with $8.82 g$ of hydrogen.

$\therefore 22.57 g$ of $P$ combines with $\frac{8.82}{91.18} \times 22.57=2.18 g$ of hydrogen

Hence the ratio between the weights of $Cl$ and $H$ which combine with a fixed wt. $(22.57 g )$ of $P$ is

$77.43: 2.18$ or $35.5: 1$.

(c) In $HCl$, the ratio between the weights of $Cl$ and $H$ is $97.23: 2.77$ or $35.5: 1$.

Since the two ratios between the weights of $Cl$ and $H$ are the same, the law of reciprocal proportions is proved.