The mole fraction of an unknown solute in 1560 g of Benzene is 0.5 . What is the molality of the solution? (M. M of Benzene:78 amu)

Step-by-step solution

Let n_B be the number of moles of Benzene and n_S be the number of moles of solute. The mass of Benzene is 1560 g and its molar mass is 78 g/mol. Thus, n_B = 1560 78 = 20 moles. The mole fraction of the solute is given as x_S = 0.5 . Since x_S + x_B = 1 , the mole fraction of Benzene is x_B = 1 - 0.5 = 0.5 . The relationship between mole fractions is n_S n_B = x_S x_B = 0.5 0.5 = 1 . Therefore, n_S = n_B = 20 moles. Molality m is defined as the number of moles of solute per kilogram of solvent. The mass of the solv