The normal boiling point of a certain liquid X is 128.10 °C, but when 35.3 g of urea (CH4N2O) are dissolved in 350. g of X the solution boils at 130.9 °C instead. Use this information to calculate the molal boiling point elevation constant K, of X. Round your answer to 2 significant digits. °C-kg ☐ x10 K-0 = mol 5

The normal boiling point of a certain liquid X is 128.10 °C, but when 35.3 g of urea (CH4N2O) are dissolved in 350. g of X the solution boils at 130.9 °C instead. Use this information to calculate the molal boiling point elevation constant K, of X. Round your answer to 2 significant digits. °C-kg ☐ x10 K-0 = mol 5

Chemistry & Chemical Reactivity

9th Edition

ISBN:9781133949640

Author:John C. Kotz, Paul M. Treichel, John Townsend, David Treichel

Publisher:John C. Kotz, Paul M. Treichel, John Townsend, David Treichel

Chapter13: Solutions And Their Behavior

Section: Chapter Questions

Problem 64GQ: The solubility of NaCl in water at 100 C is 39.1 g/100. g of water Calculate the boiling point of...

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Sodium chloride (NaCl) is commonly used to melt ice on roads during the winter. Calcium chloride (CaCl2) is sometimes used for this purpose too. Let us compare the effectiveness of equal masses of these two compounds in lowering the freezing point of water, by calculating the freezing point depression of solutions containing 200. g of each salt in 1.00 kg of water. (An advantage of CaCl2 is that it acts more quickly because it is hygroscopic, that is. it absorbs moisture from the air to give a solution and begin the process. A disadvantage is that this compound is more costly.)
The solubility of NaCl in water at 100 C is 39.1 g/100. g of water Calculate the boiling point of this solution. (Assume i = 1.85 for NaCl.)
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A forensic chemist is given a white solid that is suspected of being pure cocaine (C17H21NO4, molar mass = 303.35 g/mol). She dissolves 1.22 0.01 g of the solid in 15.60 0.01 g benzene. The freezing point is lowered by 1.32 0.04C. a. What is the molar mass of the substance? Assuming that the percent uncertainty in the calculated molar mass is the same as the percent uncertainty in the temperature change, calculate the uncertainty in the molar mass. b. Could the chemist unequivocally state that the substance is cocaine? For example, is the uncertainty small enough to distinguish cocaine from codeine (C18H21NO3, molar mass = 299.36 g/mol)? c. Assuming that the absolute uncertainties in the measurements of temperature and mass remain unchanged, how could the chemist improve the precision of her results?
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