Question

HCl contains 97.26% chlorine, phosphine contains 91.1% phosphorus. Applying the suitable law of chemical combination, calculate how much quantity of phosphorus will combine with 10.65g of chlorine to form a compound?

Answer 1

Law of chemical combination:
In modest terms, we can say that regardless of its source, and its origin, the percentage of composition of elements by weight in a given chemical compound will permanently stay the same.

Complete step by step answer:
In the question it is given that HCl contains 97.26% of chlorine, phosphine contains 91.1% phosphorus.
Chlorine in HCl = 97.26 parts and Hydrogen in HCl will be 2.74 parts.
Therefore 2.74 parts of hydrogen combines with 97.26 parts of chlorine.
One part of hydrogen reacts with a number of parts of chlorine = $\dfrac{97.26}{2.74}$= 35.5 parts.
That means 35.5 parts of chlorine reacts with 1 part of hydrogen.
Phosphorus in phosphine = 91.1 parts and hydrogen in phosphine will be 8.9 parts.
One part of hydrogen reacts with a number of parts of phosphorus = $\dfrac{91.1}{8.9}$= 10.24 parts.
That means 10.24 parts of phosphorus reacts with 1 part of hydrogen.
As per law of reciprocal proportions if phosphorus and chlorine will combine in the ratio of 10.24 : 35.5 by mass.

Therefore 35.5 g of chlorine reacts with 10.24 g of phosphorus.
We have to calculate how much quantity of phosphorus will combine with 10.65g of chlorine to form a compound.
10.65 g of chlorine will react with a number of g of phosphorus = $\dfrac{10.24}{35.5}\times 10.65\text{ }g$= 3.072 g.
So, 3.072 g of phosphorus will combine with 10.65g of chlorine to form a compound

Note: Jeremias Ritcher proposed “The law of reciprocal proportions” in 1792. If two different elements react distinctly with the same weight of a third element, then the ratio of the masses of the elements in which they react are the same.