" A student determined the molar mass of an unknown non-dissociating liquid by the method described in this experiment. She found that the equilibrium temperature of a mixture of ice and pure water was indicated to be +0.400 °C on her thermometer. When she added 11.5 g of her sample to the mixture, the temperature, after thorough stirring, fell to -4.97 °C. She then poured off the solution through a screen into a beaker. The mass of the solution was 79.97 g, and the ky of the solvent (water) is 1.86 kg °C/mol. a. What was the freezing point depression? °C b. What was the molality of the unknown liquid? m c. What mass of unknown liquid was in the decanted solution? d. What mass of water was in the decanted solution? e. How much unknown liquid would there be in a solution containing 1 kg of water, with her unknown liquid at the same concentration as she had in her experiment? g unknown liquid f. Based on these data, what value did she calculate for the molar mass of her unknown liquid, assuming she carried out the calculation correctly? g/mol

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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A student determined the molar mass of an unknown non-dissociating liquid by the method described in this experiment. She found that the equilibrium temperature of a
mixture of ice and pure water was indicated to be +0.400 °C on her thermometer.
When she added 11.5 g of her sample to the mixture, the temperature, after thorough stirring, fell to -4.97 °C. She then poured off the solution through a screen into a
beaker. The mass of the solution was 79.97 g, and the ky of the solvent (water) is 1.86 kg °C/mol.
a. What was the freezing point depression?
°C
b. What was the molality of the unknown liquid?
m
c. What mass of unknown liquid was in the decanted solution?
d. What mass of water was in the decanted solution?
e. How much unknown liquid would there be in a solution containing 1 kg of water, with her unknown liquid at the same concentration as she had in her
experiment?
g unknown liquid
f. Based on these data, what value did she calculate for the molar mass of her unknown liquid, assuming she carried out the calculation correctly?
g/mol
Transcribed Image Text:" A student determined the molar mass of an unknown non-dissociating liquid by the method described in this experiment. She found that the equilibrium temperature of a mixture of ice and pure water was indicated to be +0.400 °C on her thermometer. When she added 11.5 g of her sample to the mixture, the temperature, after thorough stirring, fell to -4.97 °C. She then poured off the solution through a screen into a beaker. The mass of the solution was 79.97 g, and the ky of the solvent (water) is 1.86 kg °C/mol. a. What was the freezing point depression? °C b. What was the molality of the unknown liquid? m c. What mass of unknown liquid was in the decanted solution? d. What mass of water was in the decanted solution? e. How much unknown liquid would there be in a solution containing 1 kg of water, with her unknown liquid at the same concentration as she had in her experiment? g unknown liquid f. Based on these data, what value did she calculate for the molar mass of her unknown liquid, assuming she carried out the calculation correctly? g/mol
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