When 3.2g of sulphur is vapourised at `450^(@)C` and 723 mm pressure , the vapours occupy a volume of 780ml. What is the molecular formula of sulphur vapours under these conditions? Calculate the vapour density also.

Explanation

`PV =nRT`
`rArr ( 723)/( 760)xx (780)/( 1000) =( 3.2)/( M ) xx 0.082 xx 723 `
M = 255.67
no. of atoms of sulpher in one molecule `=( M)/( 32) = 8`
`:. ` Molecular formula of sulphur = `S_(8)`
V.D. `= ( M)/( 2) = ( 255.67) /(2) rArr 127.835`