Question

A sample of neon effuses from a container in 76 seconds. the same amount of an unknown noble gas requires 155 seconds. part a identify the gas.

Answer 1

The rate of gas effusion or diffusion is inversely proportional to the square root of molar mass
molar mass of neon is 20
let the molar mass of unknown gas be y
155/76=sqrs of y/20
square both side to remove the square root sign
155^2/76^2 =y/20
by cross multiplication y={(24025 x 20)/5776}=83.18

the gas is krypton since 83 is one isotope of krypton

Answer 2

Answer: The other gas is Krypton (Kr).

Explanation: The rate of effusion of gas is given by Graham's Law.

Graham's Law states that the rate of effusion of gas is inversely proportional to the square root of their atomic masses.

Mathematically,

`\text{Rate of effusion}=\frac{1}{\sqrt{\text{Molar mass}}}`

Rate of effusion is the amount of gas effused in a given time 't'

Mathematically,

`\text{Rate of effusion}=(V)/(t)`

As per the question:

For Neon:

`t_1=76sec\\M_1=20`

For unknown gas:

`t_2=155sec\\M_2=?`

`V_(neon)=V_{\text{unknown gas}}`

Putting values in rate of effusion formula, we get:

`\frac{(V_(neon))/(t_1)}{\frac{V_{\text{unknown gas}}}{t_2}}=\sqrt{(M_2)/(M_1)}`

`(155)/(76)=\sqrt{(M_2)/(20)}`

`M_2=83.150`

This mass corresponds to the mass of Krypton noble gas.