A solution is prepared by dissolving 30g of urea in 120g of water .Calculate the molality of the solution . ( Molar mass of urea : 60)

Explanation

Molality ` =( "No , of moles of solute ")/(" Mass of solvent in kg") `
` "No, of moles " = ("Mass ")/( "Molecular mass " ) `
` " " = ( 30)/( 60 ) = 0.5 moles `
` "Mass of solvent in kg "= ( 120 )/( 1000) = 0.12 kg `
` " Molality "" "= ( "No. of moles of solute ")/(" Mass of solvent in kg ") `
` " "= ( 0.5)/( 0.12) = 4.166m`.