AME: SECTION: DATE: LABORATORY 3 Pre-Lab 1. In an experiment, a group of student

Question

AME: SECTION: DATE: LABORATORY 3 Pre-Lab 1. In an experiment, a group of students dissolved 4.67 g of toluene in 67.8 g of cyclohexane. What was the molality of the solution? The molar mass of toluene is 92.14 g/mol. 2. If the freezing point of the solution in question 1 was observed to be -8.6 °C, and the normal freezing point of cyclohexane is 6.50 °C, what is the value of K, for cyclohexane? When 7.94 g of xylene was added to 132.5 g of cyclohexane, the freezing point of the solution was -4.9 °C 3. a. Using the freezing point depression equation and the K, from question 2, calculate the molality of the solution. Laboratory 3 | Colligative Properties: Freezing Point Depression

Explanation / Answer

Ans 1 :

Molality = number of moles of solute / mass of solvent in kg

Moles = given mass / molar mass

n = 4.67 / 92.14 = 0.0507 mol

m = 0.0507 / 0.0678

= 0.748 m

So the molality of the solution will be 0.748 m.

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