Most students reported molecular masses larger than the actual value. What is a possible reason for this? Your answer must be specific, simply saying "students made a mistake" is not sufficient.

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
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Problem 1RQ: Define and explain the differences between the following terms. a. law and theory b. theory and...
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Most students reported molecular masses larger than the actual value. What is a possible reason for this? Your answer must be specific, simply saying "students made a mistake" is not sufficient.

Molecular Weight Determination by Freezing Point Depression
Object:
Determine the molecular mass of an unknown sample.
Procedure:
Add about 6 g of the solvent t-butanol to a test tube.
Note – (Ks= 9.1°C/m)
1.
2.
Place the test tube containing the t-butanol in a cold-water bath.
3.
Stir the liquid with a thermometer to determine the temperature in which t-butanol freezes.
Do this twice using the same sample.
4.
Remove the test tube from the cold water bath and add about 0.4 g of the unknown sample
to the liquid t-butanol. Make sure the unknown sample dissolves completely.
5.
Repeat steps 2 and 3 with the test tube containing t-butanol and the unknown sample.
Data:
Mass of solvent (t-butanol)
Freezing temperature of solvent
°C
°C
Mass of the unknown sample
g
Freezing temperature of the solution
°C
°C
Results:
Change in freezing temperature (AT;)
°C
°C
Molality (m) of unknown solution
m
m
Molecular mass of unknown sample
_g/mole
_g/mole
Transcribed Image Text:Molecular Weight Determination by Freezing Point Depression Object: Determine the molecular mass of an unknown sample. Procedure: Add about 6 g of the solvent t-butanol to a test tube. Note – (Ks= 9.1°C/m) 1. 2. Place the test tube containing the t-butanol in a cold-water bath. 3. Stir the liquid with a thermometer to determine the temperature in which t-butanol freezes. Do this twice using the same sample. 4. Remove the test tube from the cold water bath and add about 0.4 g of the unknown sample to the liquid t-butanol. Make sure the unknown sample dissolves completely. 5. Repeat steps 2 and 3 with the test tube containing t-butanol and the unknown sample. Data: Mass of solvent (t-butanol) Freezing temperature of solvent °C °C Mass of the unknown sample g Freezing temperature of the solution °C °C Results: Change in freezing temperature (AT;) °C °C Molality (m) of unknown solution m m Molecular mass of unknown sample _g/mole _g/mole
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