A `4:1` molar mixture of `He` and `CH_(4)` is contained in a vessel at `20 bar` pressure. Due to a hole in the vessel, the gas mixture leaks out. What is the composition of the mixture effusing out initially?

Explanation

The molar ratio of `He:CH_(4)=4:1`
`"Partial pressure of He"=(4)/(4+1)xx20="16 bar"`
`"Partial pressure of "CH_(4)=(1)/(4+1)xx20="4 bar"`
`"Now, "(V_(He))/(V_(CH_(4)))=(p_(He))/(p_(CH_(4)))xxsqrt((M_(CH_(4)))/(M_(He)))`
Since, time of effusion is same,
`(r_(He))/(r_(CH_(4)))=(p_(He))/(p_(CH_(4)))xxsqrt((M_(CH_(4)))/(M_(He)))`
`=(16)/(4)xxsqrt((16)/(4))=8`
`therefore" Molar ratio of mixture initially effusing out is"`
`He:CH_(4)=8:1`