Question

1) ii) A compound of X and Y has the empirical formula XY. Its vapour density is equal to
its empirical formula weight. Determine its molecular formula.​

Answer 1

Answer:

Vapour density = Molecular weight/2

Here, V.D is equal to Emp. weight (say, W)

therefore,

M/2 = W

or, M = 2W

Now, if, Molecular weight = n × emp. wieght

then,

Molecular Formula = n × emp. formula

We know that M = 2W

so n = 2

hence, molecular formula = 2 × emp. formula

So, molecular formula = X2Y2

I hope its clear to you now :)