When 12.1 g of the sugar sucrose (a nonelectrolyte)is dissolved in exactly 800.0 g of water, the solution has a freezing point of -0.082°C.What is the molar mass of sucrose? K_f of water is 1.86°C/m. A)426 g B)99.2 g C)178 g D)266 g E)343 g

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Quizplus · Accepted Answer

The freezing point depression formula is ΔTf = i * Kf * m. Since sucrose is a nonelectrolyte, i = 1. ΔTf = 0.082°C, Kf = 1.86°C/m. Solving for molality (m), m = ΔTf / Kf = 0.082 / 1.86 = 0.0441 m. Molality is moles of solute per kg of solvent, so moles of sucrose = 0.0441 m * 0.8 kg = 0.03528 moles. Molar mass = mass / moles = 12.1 g / 0.03528 moles = 343 g/mol.

When 121 G of the Sugar Sucrose (A Nonelectrolyte)is Dissolved in in Exactly