Question

Freezing point depression can be used to experimentally determine the van't Hoff factor of a solute in solution. Given the data in the table, please answer the questions below and determine the "real" van't Hoff factor of the solute. Experimental Results Mass of solvent (water) Freezing point of water Freezing point depression constant (Kf) of water Mass of solution Freezing point of solution 8.515 g 0.00°C 1.86°C/m 9.3589 -5.45°C a. What mass of solute was used? b. What is the freezing point depression, ATf, of the solution? 4.9 °C c. What is the colligative molality, mc, of the solution? 49 d. How many moles of solute particles are present in solution? 4.0 moles e. If the solute has a molar mass of 133.80, what is the van't Hoff factor, i, for the solute? (Remember that experimentally, i does not have to be an integer!)

Answer 1

Solution Man of solvent (water) = 8.515 g Max of solution - 9.358 g Plass of solute = Man of solution - Man of solvent - 9.358-8.515 T Mass of selute = 0.843 g 1 Answer of @ } Number of moles of salute Molality of solution given melar man of solute mass of solvent inkg (0.84 34 133.80 g/mol) 8.515 x 103 kg 7.399 2x 10 x 10 mal kg 0.7399 mol kg') {Amwer of @} 4 + 3 m Im = = = (0.00-(-5.45) °C freezing point depression of sehent (Experimental) (ATA) = 5.45°c gansoor of D } experimental Number of moles of selute particle = 0.843 g = 0.0063 moles answer of Af & number of moler - Man of compound 133. gogmed Molar mase of compound )

(AT8 ) cabeulate - Cikg. m where, mis molality of solution (AT) = 1.86°/m x 0.7399 x = 1.376214 ~ 1.376 °C AT) (ATA) erroringla - PATJ), calculate experimental ů = 5.45°C 10376°C i = 3.96 i ~4) Sanswer of e} i is van't Hoff factor