At `30^(@)C` and 720 mm and Hg, the density of a gas is 1.5 `g// l t`. Calculate molecular mass of the gas. Also find the number of molecules in 1 cc of the gas at the same temperature.

Explanation

Assuming ideal behaviour and applying ideal gas equation `:`
PV = nRT
Another form of gas equaiton is `P M_(0) = d RT `
`rArr M_(0)+(d RT)/( T ) = ( 1.5 xx 0.0821 xx 303)/( 720 // 760) ( T =30 + 273K)`
`rArr M_(0) = 39.38`
Now number of molecules `= n xx N_(0)`
`= (PV)/( RT ) xx N_(0) = ( 720 xx760 xx1 xx 10^(-3))/( 0.0821 xx303 ) xx 6.023xx 10^(23)`
`= 2.29 xx 10^(19)`