Freezing Point Depression Experiment

I. LIQUID - Identification of an Unknown Liquid: Using the physical properties of Solubility, Density, and Boiling Point.

29. When the thermometer reads 40°C, carry the beaker out of the heating apparatus with a beaker tong.

Place the beaker on the hot plate, place the thermometer in the beaker and set the hot plate to 5oC.

The additional ice that melted was added to the initial mass of water to obtain the final weight of water in the solution to calculate molality:

In order to fulfil the labs purpose, the lab was split into two parts. The first part consisted of measuring and determining the freezing point depression of the solution water. The second part consisted of measuring and determining the freezing point depression of a solution that consisted of water and an unknown solute.

The freezing point depression constant for water that was experimentally determined in this analysis was 0.0479 °C/m, which was derived from the slope of the trend line in Figure 4. This is significantly lower than the constant stated in the literature of 1.86 °C/m.1 The freezing point temperature determined via cryoscopy should have been much lower in the high sucrose concentration solutions.

Place the test tube containing cold water in a test tube clamp and hold the test tube above the burning alcohol. Observe the outside of the test tube for evidence of product formation.

The objectives in this laboratory were to be able to calculate the freezing point depression among three trials of unknowns, be able to correctly measure the freezing points of p-xylene, and to be able to calculate the molar masses of the unknowns by found freezing point depression values. This was done to be able to understand and apply a concept names supercooling. Supercooling is when a liquid is put far under its original freezing point and remains a liquid or gas. This happens when a substance is cooled so quickly that it’s easier for it to stay a liquid than to crystalize, until it reached its nucleation point and begins to heat up returning to its freezing point (image 4). The supercooling of p-xylene was observed in three

Purpose: The purpose of this laboratory was to gain an understanding of the differences between the freezing points of pure solvent to that of a solvent in a solution with a nonvolatile solute, and to compare the two.

Procedure: This lab starts off by making sure the logger pro and temperature probe are in proper condition. Then, the data collection must be adjusted to 15 minutes and 12 samples/ min. After that a Bunsen burner must be set up by assembling a ring-stand, ring, and wire gauze, and a crack-less beaker is used to boil some water. First the beaker and the large watch glass need to be weighed and the mass has to be recorded using a triple beam balance. Next, the beaker with 200g of ice is placed on the ring stand, and immediately heated over medium flame. An important note is to make sure the flame is perfectly adjusted so the ice does not melt on the counter while trying to adjust the flame. Furthermore, place the temperature probe in the ice so it is not resting at the bottom of the beaker, it is best to secure it with a small clamp. Additionally, click the green start button on the computer and stir continuously with a glass rod until the ice is completely melted. Once the ice has melted which is somewhere between 3-5 minutes, the stirring rate will slow

4. Remelt the contents of the tube and add the counterpart component based on the given schedule. Ask the demonstrator to adjust the cooling water between mixtures. During the experiment, record and plot the data obtained for all mixtures listed. The experiments are stopped as follows:

Introduction Molar mass is a fundamental quantity of chemistry. There are multiple ways to find the molar mass of a substance experimentally; one way is to use Freezing Point Depression by using the following equation: ΔT= kf*m (Robinson, 2018). The purpose of this lab was to do just that; measure the freezing point depression of a solution when a solute is added to a solvent, and from that, determine the molar mass of an unknown substance, along with learning about the influence that solutes have on liquid properties. A concept of importance to this experiment is freezing point. According to LibreTexts, “Freezing point depression is a colligative property observed in solutions that results from the introduction of solute molecules to a solvent…and

As stated, our solvent in this lab will be tert-butanol. We start by recording the freezing point of this substance without anything added. Then, we add various

Add 2 drops of soap to the removed test tube, and place it in the test tube holder.

Once the range is obtained, remove the thermometer and beaker. Pour out the hot water and allow both the thermometer and the beaker to cool. Once cool, repeat the previous steps with the second compound, tetradecanol. At the conclusion of the second experiment, repeat the steps for a third and final time using an equal mixture of both compounds. Be sure to record the melting point range for all three experiments.