An aqueous solution containing `288` gm of a non-volatile compound having the stoichiometric composition `C_("x")H_(2"x")O_("x")` in `90` gm water boils at `101.24^(@)"C"` at `1.00` atmospheric pressure. What is the molecular formula ?
`"K"_(b)("H"_(2)O)=0.512"K mol"^(-1)"kg"`
`"T"_(b)("H"_(2)O)=100^(@)"C"`

Answer

`C_(44)H_(88)O_(44)`

Explanation

Elevation in B.P. `= 101.24 – 100 = 1.24°`C
`"m"_("solute")=12"x"+2"x"+16"x"=30"x"`
`Delta"T"_("b")="K"_("b")xx("w"_("solute")xx1000)/("m"_("solute")xx"w"_("solvent"))`
`1.24=0.512xx(288xx1000)/(30"x"xx90)`
`"x"=44`
`therefore` Molecular formula of compound `="C"_(44)"H"_(88)"O"_(44)`