In a solution of 7.8 g of benzene (C₆H₆) and 46 g of toluene (C₆H₅CH₃), the mole fraction of benzene is

amount of a constituent in moles mole fraction = total amount of all constitutents in a mixture in moles Number of moles of 6 6 7.8 0.1 78 C H Number of moles of 6 5 3 46 0.5 92 C H CH Total moles 0.6 6 6 0.1 1 0.6 6 C H