What is the freezing point depression constant of stearic acid?

69.0◦C
Stearic acid, CH3(CH2)16COOH, is also known as n-octadecanoic acid and has a freezing point of 69.0◦C and a kf of 4.5◦C/m. Lauric acid, CH3(CH2)10COOH, is also known as dodecanoic acid has a van’t Hoff factor (i) of 1.

What is the KF for stearic acid?

4.5 °C kg /
A researcher takes 5.00 g of tridecanoic acid (MW = 214.34 g / mole) and dissolves it in 20.0g of stearic acid (kf = 4.5 °C kg / mole).

How do you find the freezing point depression constant?

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.

Does freezing point depression change constant?

The freezing point depression constant changes depending on the solvent, and the van ‘t Hoff factor accounts for the number of particles that a dissolving solute creates in solution.

What is the freezing point depression constant of lauric acid?

3.9˚C
The freezing-point depression constant (Kf) for lauric acid is given (3.9˚C•kg/mol).

What is the value of KF?

1.86^o
The value of Kf for water is 1.86^o , calculated from glucose solution.

Does every solvent have the same freezing point depression constant?

The proportionality constant, Kf, is called the molal freezing-point depression constant. It is a constant that is equal to the change in the freezing point for a 1-molal solution of a nonvolatile molecular solute. Every solvent has a unique molal freezing-point depression constant.

What factors affect the freezing point depression of a solution?

The freezing point of the solvent in a solution changes as the concentration of the solute in the solution changes (but it does not depend on the identity of either the solvent or the solute(s) particles (kind, size or charge) in the solution).

How do you find freezing point of lauric acid?

The freezing point of lauric acid is 44 °C, based on the plateau observed at this temperature on the graph. observed on the graph at this temperature. 6. Freezing point depression: 44 °C – 42 °C = 2 °C.

How do you find the KF of lauric acid?

Calculate molality (m), in mol/kg, using the formula Δt = Kf * m. The Kf value for lauric acid is 3.9°C•kg/mol.

How is the molal freezing point depression constant related?

The molal freezing depression constant of a solvent is related to the latent heat of fusion for that substance. = the heat of fusion of the solvent in Joules/gram or calories/gram For example, water has a latent heat of fusion of 79.71 cal/gram and freezes at 0 °C (273.2 K).

Which is used to predict freezing point depression?

In this experiment, the colligative molality of a stearic acid solution containing lauric acid will be used to predict the freezing point depression. Then, this prediction will be compared to the experimentally measured freezing point of the solution.

How to calculate the freezing point of a nonelectrolyte?

Sample Problem: Freezing Point of a Nonelectrolyte 1 List the known quantities and plan the problem. Known mass C 2 H 6 O 2 = 400. 2 Solve. The normal freezing point of water is 0.0°C. Therefore, since the freezing point decreases by 24.0°C, the freezing point of the solution is -24.0°C. 3 Think about your result.