The rate of diffusion of a unknown gas and chlorine are in the ratio 6:5.veper density of chlorine is 36.find out the molecular weight of unknown gas?

1 Answer
May 14, 2018

50

Explanation:

From Graham's Law of Diffusion,

We know,

The rate of diffusion of a gas is inversely proportional to the square root of molecular weight of the gas.

So, We get,

r prop 1/sqrt(M)

From that, we get,

r_1/r_2 = sqrt(M_2/M_1)....................................(i)

Now, We know, "Molecular Weight" = 2 xx "Vapour Density".

So, Average Molecular Weight of Chlorine = 2 xx 36 = 72

Now, From (i),

color(white)(xxx)6/5 = sqrt(72/M_"unknown")

rArr 36/25 = 72/M_"unknown" [Squaring both sides]

rArr 25/36 = M_"unknown"/72

rArr M_"unknown" = (25 * cancel(72)^2)/cancel(36)

rArr M_"unknown" = 50

So, The Molecular Weight of the Unknown Gas is 50.

Hope this helps.