What is the purpose of the freezing point depression lab?
PURPOSE/INTRODUCTION The purpose of this experiment is to determine the molecular weight of an unknown substance by measuring the freezing point depression of an aqueous solution of the unknown.
How do you determine freezing point experimentally?
In order to determine the freezing point of this pure solvent you must first heat it in a test tube to over 60 °C using a hot water bath, and then measure the temperature as a function of time as the liquid cools. At first the temperature will fall quite rapidly.
How does molar mass affect freezing point?
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.
What is meant by freezing point depression?
Freezing Point Depression. Freezing Point Depression. The freezing point of a solution is less than the freezing point of the pure solvent. This means that a solution must be cooled to a lower temperature than the pure solvent in order for freezing to occur.
How many determinations of a freezing point should you do explain?
You should have two significant figures in your freezing point temperature. If you need to repeat a trial to get better data, warm the test tube and then put it back into the ice bath. Repeat the experiment enough times so that your data are accurate and reproducible.
How does freezing point affect molar mass?
What is RAST method?
Rast method is actually a micro-method because only a few milligrams of the solute are required. It means that when one mole of a solute is dissolved in one kilogram of camphor, the depression in freezing point is 40″C, which can be read using an ordinary thermometer.
Does molar mass affect freezing point depression?
How does molar mass affect the freezing point?
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.
What does melting point depression mean?
Melting-point depression is the phenomenon of reduction of the melting point of a material with reduction of its size. This phenomenon is very prominent in nanoscale materials, which melt at temperatures hundreds of degrees lower than bulk materials.
What is molal depression constant?
Molal depression constant is defined as the depression in freezing point produced when 1 mole of solute is dissolved in one kg (1000 g) of the solvent. molal depression constant kf is defined as the depression in the freezing point of a solution whose molality is one .