What is the freezing point depression for cyclohexane?
20.2 °C-
The freezing point depression constant of cyclohexane is 20.2 °C-kg per mol of solute.
How does molar mass affect freezing point depression?
Thus, as the molar mass increases, the freezing point depression decreases. That is, increasing the molar (or molecular) mass will have a smaller effect on the freezing point.
How do you calculate molar freezing point?
The freezing point depression ∆T = KF·m where KF is the molal freezing point depression constant and m is the molality of the solute. Rearrangement gives: mol solute = (m) x (kg solvent) where kg of solvent is the mass of the solvent (lauric acid) in the mixture. This gives the moles of the solute.
Why is freezing point depression a colligative property?
The freezing point depression thus is called a colligative property. The explanation for the freezing point depression is then simply that as solvent molecules leave the liquid and join the solid, they leave behind a smaller volume of liquid in which the solute particles can roam.
What is the unit of freezing point depression?
Kf is the molal freezing point depression constant of the solvent (1.86 °C/m for water). m = molality = moles of solute per kilogram of solvent.
How to calculate molar mass by freezing point depression?
The next exercise illustrates how to use the experimentally measured decrease of freezing point, ∆Tf, to calculate the molar mass of an unknown nonvolatile nondissociating solute. Exercise: The freezing point of cyclohexane is 6.50 °C. A solution is prepared by dissolving 0.5580g of an unknown solute in 33.50 g cyclohexane.
Which is the freezing point depression constant for cyclohexane?
KF is called the freezing point depression constant. KF = 20.0 oC/m for cyclohexane. m is the molality of the solution. You will measure or be given everything in Equations 1 and 2 except for the moles of the solute (your unknown). You will solve Equation 1 for the molality, m, of your solution.
Why is cyclohexane used as the solvent during the?
Answer Wiki. Probably because cyclohexane is much, much closer to an ideal liquid than water. Water has a number of anomalous properties and its behavior is quite nonideal for freezing point depression purposes.
How to calculate the molar mass of cyclohexane?
Calculate the molar mass of the unknown solute. Kf for cyclohexane is 20.0 °C.kg/mole. Setup: a) Find the molality of the solution: ∆Tf = Kf m molality = ∆Tf = 2.18 °C = 0.109 mole solute/kg Kf 20.0 °C.kg/mole b) Find the number of moles of solute dissolved in 52.4 g H2O: