Phosphorus trichloride (PCl_(3)) contains 22.57 % of phosphorus, phosphine (PH_(3)) contains 91.18 % of phosphorus. Hydrochloric acid (HCl) contains 97.23 % of chlorine. Show that the data is according to the Law of Reciprocal Proportions.

Phosphorus trichloride (PCl_(3)) contains 22.57 % of phosphorus, phosp

1.	Phosphorus trichloride (PCl_(3)) contains 22.57 % of phosphorus, phosphine (PH_(3)) contains 91.18 % of phosphorus. Hydrochloric acid (HCl) contains 97.23 % of chlorine. Show that the data is according to the Law of Reciprocal Proportions.
Answer» Solution :Let US FIX `1g` of phosphorus (P) as the FIXED weight In phosphorus trichloride `(PCl_(3))` Weight of phosphorus `= 22.57 g` Weight of chlorine `= 100 - 22.57` `=77.43 g` `22.57 g` of phosphorus have combined with chlorine `= 77.43 g` `1.0 g` of phosphorushas combined with chlorine `= (77.43)/(22.57)g=3.43g` In phosphine `(PH_(3))` Weight of phosphorus `= 91.18 g` Weight of HYDROGEN `=100-91.18 = 8.82 g` `91.18 g` of phosphorus have combined with hydrogen `=8.82 g` `1.0 g` of phosphorus has combined with hydrogen `= (8.82)/(91.18)g=0.097g` Thus, the ratios by weights of chlorine and hydrogen combining with a fixed weight of phosphorus in the two compounds is : `3.43 : 0.097` (This ratio is not the same)...(i) In hydrochloric acid gas `(HCl)`, Weight of chlorine `=97.23 g` Weight of hydrogen `=100-97.23 = 2.77 g` Thus, chlorine and hydrogen have combined in the ratio `97.23 : 2.77` ....(ii) Let us compare the two ratios. These are RELATED to each other as : `(3.43)/(0.097):(97.23)/(2.77)or35.37:35.10or 1:1("approximately")` Since these two ratios are nearly the same `(1:1)`, the data is according to the Law of Reciprocal Proportions.