A certain gas occupies 0.418 litres at `27^@C` and 740 mm Hg.
If the same gas weighs 3.00 g, what is its molecular weight?

Answer

181.5

Explanation

Number of moles in 3.00 g of gas = `(3.00)/M`, where M is the
molecular weight of the gas. According to the gas equation
`PV = nRT`
Substituting the values, we have `740/760 xx 0.418 = 3.00/M xx 0.0821 xx 300`
(P = 760/760 atm )
`:. " " M = 181.5`