What mass in grams of a molecular substance (molar mass = 50.0 g/mol)must be added to 500 g of water to produce a solution that boils at 101.56 °C? [K_b(water) = 0.512 °C m^-1]

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Quizplus · Accepted Answer

The boiling point elevation formula is ΔT = i * Kb * m. Here, ΔT = 101.56 - 100 = 1.56°C, Kb = 0.512°C m^-1, and i = 1 (non-electrolyte). Solving for m (molality), m = ΔT / Kb = 1.56 / 0.512 = 3.05 mol/kg. For 0.5 kg of water, moles of solute = 3.05 * 0.5 = 1.525 mol. Mass = moles * molar mass = 1.525 * 50 = 76.25 g.

What Mass in Grams of a Molecular Substance (Molar Mass