Thyroxine,an important hormone that controls the rate of metabolism in the body,can be isolated from the thyroid gland.If 0.455 g of thyroxine is dissolved in 10.0 g of benzene,the freezing point of the solution could be measured as 5.144°C.Pure benzene freezes at 5.444°C and has a value for the molal freezing point depression constant of K_f of 5.12°C/m.What is the approximate molar mass of thyroxine? A)7.77 $\times$ 10⁵ g/mol B)777 g/mol C)7.77 g/mol D)11.3 g/mol E)42.8 g/mol

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Quizplus · Accepted Answer

The molar mass of thyroxine can be calculated using the formula ΔTf = i * Kf * m, where ΔTf is the freezing point depression, Kf is the molal freezing point depression constant, and m is the molality of the solution. Given ΔTf = 5.444°C - 5.144°C = 0.3°C, Kf = 5.12°C/m, and the mass of thyroxine is 0.455 g dissolved in 10.0 g of benzene, we can find the molality and then calculate the molar mass. The calculation yields a molar mass of approximately 777 g/mol.

Thyroxine,an Important Hormone That Controls the Rate of Metabolism in the Body,can