Question

Two perfumes are released at the same time. If one is standing 7.5 m from the point of release. Perfume A (molar mass 275 g/mol) and perfume B (molar mass 205 g/mol) at the same temperature. I. Which perfume will the person smell first and why?

Answer 1

According to Graham's Law of Diffusion," Diffusion of Gas is inversely proportional to square root of its Molecular Mass or Density".

rᵇ/rᵃ =
`√(da/db)`
Or,
rᵇ/rᵃ =
`√(Ma/Mb)` ----- (1)
As,
Ma = 275 g/mol

Mb = 205 g/mol

Putting Values in eq.1,

rᵇ/rᵃ =
`√(275/205)`

rᵇ/rᵃ = 1.15

Result:
Perfume B will diffuse 1.15 times faster than Perfume A. Hence, Perfume B will be first smelled by the person.