| 1. | Safety |
| 2. |
Objectives/Overview |
| 3. |
Procedures |
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4. |
Observations |
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| 8. | Conclusions |
| 9. | Calculations/Set-Ups |
| 10. | Grading Scale |
| 11. | Review Prelab Questions |
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12. |
Review Postlab Questions |
Experiment
14
Using
Freezing Point Depression to Find Molecular Weight
PRE-LABORATORY QUESTIONS
References:
Brown, Lemay, and Bursten, Chemistry the Central Science, 8th ed.
(2000)
pp. 486-489 (colligative properties)
pp. 490-491 (freezing point depression)
Learning Center: answers to pre- and post-lab questions.
SHOW SET-UP FOR ALL CALCULATION PROBLEMS
Calculate the molecular mass of an unknown compound given the following data from a freezing point depression experiment:
0.845 g of the unknown dissolved in 4.250 g of camphor had a freezing point of 1.36°C. The freezing-point depression constant for camphor is 40.°C.kg/mol and the melting point of pure camphor is 129°C.
1. Calculate the freezing temperature depression, ŠT
2. Calculate the molality
3. Calculate the number of moles present of the unknown compound
4. Calculate the experimental molar mass of the unknown compound
