Two elements P and Q form the compounds P_(2),Q_(3) , and PQ_(2). If 0.15 mole of P_(2),Q_(3), weighs 15.9 g and 0.15 mole of PQ_(2) weighs 9.3 g, find the atomic weights of P and Q.

Two elements P and Q form the compounds P_(2),Q_(3) , and PQ_(2). If 0

1.	Two elements P and Q form the compounds P_(2),Q_(3) , and PQ_(2). If 0.15 mole of P_(2),Q_(3), weighs 15.9 g and 0.15 mole of PQ_(2) weighs 9.3 g, find the atomic weights of P and Q.
Answer» Solution :Molecular weight of `P_(2),Q_(3)` = wt. of 1 mole `(15.9xx1)/(0.15) = 106.` Molecular weight of `PQ_(2)` = wt. of 1 mole =`(9.3xx1)/(0.15) = 62.` SUPPOSE that the atomic WEIGHTS of P and Q are RESPECTIVELY x and y. Thus, 2x + 3y = 106 `(P_(2)Q_(3) =106)` x + 2y = 62. `(PQ_(2) = 62)` On solving: x = 26 y = 18.