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α-Tocopherol is the most commonly found naturally-occurring form of vitamin E. Its elemental composition is 80.85 % C, 11.72 % H, and 7.43 % O. A solution of 9.85 g α-tocopherol in 215 g cyclohexane freezes 2.15 °C below the actual freezing point of cyclohexane. Calculate the molecular weight and molecular formula of α-tocopherol. (Kf for cyclohexane is 20.2 °C•kg/mol)
When 9.5 g of lithium stearate (LiC18H35O2, MW = 290.47 g/mol) is dissolved in 550 g benzene, the resulting solution freezes at 0.30 °C lower than pure benzene (FP = 5.5 °C). Calculate the value of Kf (freezing point constant) for benzene.
Determine the freezing and boiling points of a solution composed of 15.0 g octane (C8H18) dissolved in 5.00 mol cyclohexane.
Hydrofluoric (HF) only partially dissociates when dissolved in water according to the equation: HF ⇌ H+ + F–. A 76.58 g of HF was dissolved in 1500 g of water to make a solution. The freezing of the solution is –4.926°C. Determine the fraction of HF dissociated.
