Question

The molar masses of four unknown gases are shown in the table.

Molar Mass of Unknown Gases
Gas Molar Mass
A 44 g/mol
B 20 g/mol
C 30 g/mol
D 32 g/mol
Which gas is likely to have the lowest rate of diffusion?
a. Gas A
b. Gas B
c. Gas C
d. Gas D

Answer 1

a. Gas A has the lowest rate of diffusion

Further explanation

Given

The molar masses

Required

the lowest rate of diffusion

Solution

Graham's law: the rate of effusion of a gas is inversely proportional to the square root of its molar masses or

the effusion rates of two gases = the square root of the inverse of their molar masses:

`\rm (r_1)/(r_2)=\sqrt{(M_2)/(M_1) }`

So :

`\tt r\approx (1)/(√(M) )`

The greater the molar mass, the smaller the rate

So gas A has the lowest rate