Question

The density of gas A and gas B is in the ratio 1:2. If the molecular mass of A is 4 times that of B, then ratio of partial pressure of A to that of B will be:

Answer 1

Solution :-

As per the given question,

• Da / Db = 1 :2

Ma = 4 Mb

• Ma /Mb =4

As per the ideal gas equation ,

➝ PV = nRT

here ,

• P = pressure
• V = Volume
• n = moles
• R = gas constant
• T = temperature

we know that ,

➝ n = W /M

here ,

• W = mass
• M = molecular mass

Hence ,

➝ PV = WRT / M

➝ PM = W/V x RT

we know that ,

➝ D = W / V

here ,

• W = mass
• V = Volume

Hence ,

➝ PM = DRT

From this we can conclude that ,

➝ P ∝ D / M

➝ Pa / Pb = Da / Db x Mb / Ma

➝ Pa / Pb = 1 / 2 x 1 / 4

➝ Pa / Pb = 1 / 8