Two solutions are prepared using the same solute: solution a.0.27 g of the solute dissolves in 27.4 g of t-butanol solution b.0.23 g of the solute dissolves in 24.8 g of cyclohexane which solution has the greatest freezing point change?

The freezing point depression is calculated through the equation,

     ΔTf = (Kf)(m)

where ΔTf is freezing point depression, Kf is the molal freezing point depression and m is the molality of the solute. Using the givens above and the equation,

a. Let x be the molar mass of the solute. The Kf of t-butanol is 9.1 °C/m.
      ΔTf = (9.1)(0.27/x)(1/0.0274)
      ΔTf = 89.67/x

b. Let x be the molar mass of the same solute. Kf value of 20.1 °C/m
     ΔTf = (20.1)(0.23/x)(1/0.0248)
     ΔTf = 186.4/x

The answer would be letter B.