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Q#
Question Text
4)
Part I. The expresssion for the freezing point depression of a solution relative to that of the pure solute is
shown above. From solutions of known concentrations of
p
dichlorobenzene in cyclohexane, you
determine K
f
, the freezing point depression constant of cyclohexane.
What assumption is necessary in order to do these calculations?
Enter your answer in the text box displayed.
Your Answer:
In order to do calculations, the assumption
required deals with the variable i, the van't Hoff i factor. We
need to assume how many parts dicholorobenzene is capable of
breaking up into. In this particular case, we assume that the
molecule is incapable of breaking apart, and thus, would have a
van't Hoff i factor of 1.
Text Answers to be Scored by your TA
5)
Data Entry  No Scoring
Part I. How many trials of the determination of the freezing point of cyclohexane did you perform?
n =
Your Answer:
3
No Points Possible
6)
Data Entry  No Scoring
Part I. Please enter the values in Celsius to the nearest 0.2
o
that you obtained for the freezing point of
cyclohexane for each of the NCount trials you performed.
T
f
=
Your Answer:
5
No Points Possible
Your Answer:
5
No Points Possible
Your Answer:
5
No Points Possible
7)
Scoring Scheme: 3321
Part I. Please enter the result for the average of the trials of your determination of the freezing point of
cyclohexane in Celsius to the nearest tenth of a degree.
T
f
=
Your Answer:
5
You Scored
3
points out of
3
Possible
8)
Data Entry  No Scoring
Part I. Please enter the volume in mL of cyclohexane to the nearest hundredth of a mL, e.g. 9.99 mL, that
you used to prepare the pdichlorobenzene solution, the freezing point of which you subsequently
measured.
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View Full Document Volume (ml) =
Your Answer:
9.85
No Points Possible
9)
Scoring Scheme: 21
The density of cyclohexane may be taken to be 0.7726 g/mL. Considering the volume of cyclohexane that
you used to prepare the the pdichlorobenzene solution, calculate the mass in grams of cyclohexane.
Enter the mass to the nearest thousandth of a gram.
mass cyclohexane (g) =
Your Answer:
7.61
You Scored
2
points out of
2
Possible
10) Data Entry  No Scoring
Part II. Please enter the mass of
p
dichlorobenzene that you used to prepare your solution in part II of the
experiment to a thousandth of a gram, e. g. 0.577 g.
mass
p
dichlorobenzene (g) =
Your Answer:
0.5210
No Points Possible
11) Scoring Scheme: 3321
Part II. The molality of a solution is the number of moles of the solute that is dissolved in 1000 g of solvent.
Using the values for the mass of
p
dichlorobenzene, its molar mass (147.01 g/mol), and the mass of
cyclohexane solvent that you used, calculate and enter the molality of the
p
dichlorobenzene solution to
three significant digits, e.g. 0.484
m (mol/kg) =
Your Answer:
0.4660
You Scored
3
points out of
3
Possible
12) Data Entry  No Scoring
Part II. How many trials of the determination of the freezing point of your solution of
p
dichlorobenzene in
cyclohexane did you perform?
n =
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This note was uploaded on 02/09/2010 for the course CHEM 35985 taught by Professor Osterloh during the Spring '10 term at UC Davis.
 Spring '10
 OSTERLOH

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