question_answer 3)

Calculate the mole fraction of benzene in solution containing 30% by mass of it in carbon tetrachloride.

Answer:

30% of benzene in carbon tetrachloride (by mass) means that 30 g of benzene is present in 100 g solution. Mass of solution = 100 g Mass of benzene in the solution = 30 g   Mass of carbon tetrachloride = 100g ? 30g = 70g Molar mass of benzene (C6H6) = 78 g mol?1 Molar mass of CCl4 = 12 + 4 x 35.5 = 154 g mol?1  No. of moles of benzene (nC6H6) No. of moles of CCl4 (nCCl4) Mole fraction of benzene Mole fraction of CCl4 = 1 ? 0.458 = 0.542