Answer:
There are 1.29 moles of toluene in the solution.
Explanation:
m = ∆Tb/Kb
m is molality of the solution
∆Tb is the change in boiling point of cyclohexane = 90.3 ° C - 80.9 °C = 9.4 °C
Kb is the boiling point elevation constant of cyclohexane = 2.92 °C/m
m = 9.4/2.92 = 3.22 mol/kg
Number of moles of toluene = molality × mass of cyclohexane in kilogram = 3.22 × 401/1000 = 1.29 moles