What is the vapor pressure at 20°C of an ideal solution prepared by the addition of 4.50 g of the nonvolatile solute urea,CO(NH₂)₂,to 22.7 g of methanol,CH₃OH? The vapor pressure of pure methanol at 20°C is 89.0 mmHg. A) 8.51 mmHg B) 64.9 mmHg C) 74.3 mmHg D) 80.5 mmHg E) 24.1 mmHg

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The vapor pressure of the solution is calculated using Raoult's Law: P_solution = X_solvent * P_pure_solvent. First, calculate the moles of methanol and urea. Methanol: 22.7 g / 32.04 g/mol = 0.708 mol. Urea: 4.50 g / 60.06 g/mol = 0.075 mol. Mole fraction of methanol: 0.708 / (0.708 + 0.075) = 0.904. P_solution = 0.904 * 89.0 mmHg = 80.5 mmHg.

What Is the Vapor Pressure at 20°C of an Ideal