Question

A solution contains 65.0 g of solvent. How much solute is present in the solution if the mole fraction of the solute is 0.135? (molar mass of solvent=18g/mol; molar mass of solute 30g/mol)

Answer 1

mole fraction of solute = moles of solute /( moles of solute + moles of solvent )

(mole fraction of solute× moles of solute) + (mole fraction of solute × moles of solvent) = moles of solute

moles of solvent = 65.0g /18g/mol = 3.611

mole fraction of solute = 0.135

substitute the values

moles of solute = (0.135× moles of solute ) + (0.135× 3.611)

0.865 moles of solute = 0.4875

moles of solute = 0.5636

mass of solute = moles of solute × molar mass of solute

mass of solute = 0.5636mol × 30g/mol

mass of solute = 16.9g