1.00 g of a chloride of an element contains 0.835 g of chlorine. If the vapour density of the chloride is 85, find the atomic weight of the element and its valency.

1.00 g of a chloride of an element contains 0.835 g of chlorine. If th

1.	1.00 g of a chloride of an element contains 0.835 g of chlorine. If the vapour density of the chloride is 85, find the atomic weight of the element and its valency.
Answer» Solution :LET the formula of the chloride be `MCI_(X)` where x is the valency of the ELEMENT M. `x XX ` moles of M =1 `xx` moles of CI or `x xx (1-0.835)/("at . Wt . Of M)= (0.835)/(35.5)` Now we know molecular weight `= 2xx ` vapour density `=2xx85 =170` For `MCI_(x)` mol . wt. of `MCI_(x)` = at . wt. of M +x `xx` at . wt. of CI or 170 =at .wt . of M + 35.5 x. `:. ` at . wt. of M = 170 - 35.5 x or `x = (170-"at .wt.of M")/(35.5)` From (1) and (2), we get, at. wt. of M = 28.05. Substituting at. wt. of M in the eqn. (1) we get, x = 4.