Given that the vapor pressure of water is 17.54 torr at 20 °C, calculate the vapor-pressure lowering of aqueous solutions that are 2.40 m in sucrose, C,H0, and calcium chloride. STRATEGY 1. Determine the colligative molality of each solution. 2. Convert each colligative molality to a mole fraction. 3. Apply Raoult's law. Step 1: Sucrose is a nonelectrolyte whereas CaCl, has 3 ions per formula unit. sucrose: 2.40 m • CaCl,: 3(2.40 m) = 7.20 m %3D Step 2: Molality is the number of moles of solute per kilogram of solvent. 1000 g 1 kg H,O x 1 mol 18.0148 g 55.5099 mol H,O %3! 1 kg 2.40 mol Xsucrose = = 0.0414 (2.40 + 55.5099) mol 7.20 mol = 0.115 %3D %3D (7.20 +55.5099) mol Step 3: Calculate the vapor-pressure lowering at 20 °C.

Given that the vapor pressure of water is 17.54 torr at 20 °C, calculate the vapor-pressure lowering of aqueous solutions that are 2.40 m in sucrose, C,H0, and calcium chloride. STRATEGY 1. Determine the colligative molality of each solution. 2. Convert each colligative molality to a mole fraction. 3. Apply Raoult's law. Step 1: Sucrose is a nonelectrolyte whereas CaCl, has 3 ions per formula unit. sucrose: 2.40 m • CaCl,: 3(2.40 m) = 7.20 m %3D Step 2: Molality is the number of moles of solute per kilogram of solvent. 1000 g 1 kg H,O x 1 mol 18.0148 g 55.5099 mol H,O %3! 1 kg 2.40 mol Xsucrose = = 0.0414 (2.40 + 55.5099) mol 7.20 mol = 0.115 %3D %3D (7.20 +55.5099) mol Step 3: Calculate the vapor-pressure lowering at 20 °C.

Chemistry

10th Edition

ISBN:9781305957404

Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Publisher:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Chapter1: Chemical Foundations

Section: Chapter Questions

Problem 1RQ: Define and explain the differences between the following terms. a. law and theory b. theory and...

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