1 gm of chloride of an elements contains 0.835 gym of chlorine. If the vapour density of chlorideis 85, find the atomic weight of the element & its valency.

Dear Student,

Please find below the solution to the asked query:

Relationship between molecular mass and vapour density(V.D.):

V.D. = Molecular mass/2

We are given that, vapour density of metal chloride = 85 

Therefore, molecular mass of metal chloride = 85 × 2 = 170 g/mol

Given, mass of metal chloride = 1 g
Mass of chlorine in 1 g metal chloride = 0.835 g
Thus, mass of metal in 1 g metal chloride = 1 − 0.835 = 0.165 g

Let us suppose that x is the valency of the metal and the formula of metal chloride be (M^x+Cl_x) . So, atomic weight of the metal will be (Equivalent weight of metal * Valency of metal). 

Molar mass of metal chloride = 7.01x + 35.5x = x(7.01+35.5) = 42.5x

This molar mass of metal chloride should be equal to 170g/mol.

42.5x = 170g / mol
x = 170/42.5
x = 4

Therefore, the formula of metal chloride is MCl₄. 

Atomic weight of metal = 7.01 x 4 = 28.04 g

Hope this information will clear your doubts.

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