Molar Mass Determination by Freezing Point Depression
Introduction
The purpose of this experiment is to determine the torpedo freshet of camphor by determining the freeze signalise stamp of cyclohexane. In this experiment a sample of the solvent cyclohexane was cooled to its halt point and a cooling curve was constructed. A know mass of camphor was added to the known mass of camphor and the freezing point of the origin was determined using equations 1 and 2. From the freezing point falling off the molality of the camphor can be calculated and then the zep mass, by using equation 3.
If Tf(solvent) is defined as the freezing point of the pure solvent, and if Tf(solution) is defined as the freezing point of the solution, then the freezing point first gear (in °C) is given by equation 1:
?Tf = Tf(solvent) - Tf(solution) (1)
The freezing point depression ?Tf is think to m, the molality of the solution particles, given in equation 2:
?Tf = Kf m (2)
If a known mass of a solute is laid into a known mass of solvent, and the freezing point depression relative to the pure solvent determined, then the molar mass (MM) of the solute can be determined by using the separate Kf value for the solvent, equation 3:
?Tf = Kf (mol/kg solvent) = Kf (g solute/MM solute) / kg solvent (3)
Procedure
Determination of the Freezing Point of Cyclohexane
A 20 x 50 mm tribulation pipework was rinsed clean with cyclohexane. Then the tally tube, stopper, and a 150 ml beaker were weighed on a top loading balance. Approximately 4.9 grams of cyclohexane was added to the test tube then the tube, stopper, and beaker was reweighed. A salt-ice bath was prepared with well-nigh 45 g of rock salt added to a 1 L beaker filled with two-thirds full of ice. Data collection started when the cyclohexane test tube with...If you want to get a full essay, straddle it on our website: Orderessay
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