lab 2 - Q# Question Text 4) Part I. The expresssion for the...

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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: 3-3-2-1 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 p-dichlorobenzene solution, the freezing point of which you subsequently measured.
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Volume (ml) = Your Answer: 9.85 No Points Possible 9) Scoring Scheme: 2-1 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 p-dichlorobenzene 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: 3-3-2-1 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.

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lab 2 - Q# Question Text 4) Part I. The expresssion for the...

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