Freezing Point Depression Lab

The reaction "ICE" table demonstrates the method used in order to find the equilibrium concentrations of each species. The values that come directly from the experimental procedure are found in the shaded regions. From these values, the remainder of the table can be completed.

A plastic transfer pipette was used to put approximately 2 mL of p-xylene, obtained from the fume hood, into a clean, dry polypropylene test tube. The calibrated temperature probe was dried carefully with a paper towel, and then was put in the test tube. The measurement program was started and the test tube was lowered into an ice water bath, with the p-xylene in the test tube being below the surface level of the ice water. The p-xylene was stirred continuously with the temperature probe until the temperature graph leveled off. The program was stopped and the data was taken for 10 or 15 seconds after the graph leveled off. The p-xylene test tube was put in a beaker until the p-xylene thawed, and then was poured into the waste jar. The test was put in the box provided for used test tubes in the fume hood. To determine the freezing point of p-xylene, the range of data where the temperature had leveled off was used to obtain the average by clicking on Column

The mixture was transferred to an ice bath to crystallize the product, after which the product was collected by vacuum filtration on a Hirsch funnel, washing the flask with small aliquots of cold xylene and pouring the solution over the crystals, allowing the vacuum to thoroughly dry the product. Additional drying was achieved by transferring the product to filter paper and pressing the crystals to remove any excess moisture. The product was then weighed and a melting point determined. A comparative TLC was run in Hexanes:Ethyl Acetate solvent against maleic anhydride to verify the purity of the

The freezing point constant (Kf) of water is 1.86 °C m-1. Each mass amount and Van’t Hoff factor was calculated then analyzed in a table.

The first part of the lab began by one lab member adding 10.0 mL of DI water to a test tube while another lab member obtained a beaker full of ice and salt. After both these steps were complete the test tube was put in the beaker full of ice. Immediately following the test tube be being placed in the beaker, a temperature probe was inserted into the test tube. The initial temperature was recorded and after the temperature was recorded in 30 second increments. Once the water exhibited supercooling and then remained consistent at .1 °C for 3 readings it was determined that the water had froze and formed crystals. Evidence that crystals formed allowed for it to be confirmed that the water actually hit freezing point at .0

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.

The melting point of the final product, diphenylacetylene, was found to be 65-68 degrees Celsius which is right around the ideal 61 degrees Celsius melting point; this shows that purification during the lab worked and that the sample was almost 100% pure. Since only 0.01g of diphenylacetylene was collected and the theoretical yield was calculated to be 0.049g, this experiment had a 20.41% yield. A few sources of error that explain the low percentage could be the loss of crystals when transferred from the test tube to the suction apparatus or when they were transferred from the suction apparatus to the filter paper to be dried and then weighed. Crystals could have also been lost if more than 5 drops of methanol was added because excess methanol would dissolve the crystals. The experiment was successful when looking at the crystals collected from the addition step and the elimination step; however, to improve the percent yield and collected product the the test tubes could have been allowed to cool down in the ice bath past the 5 minutes to ensure all the crystals formed

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

The product that was obtained from the experiment was analyzed by weighing the product, obtaining melting point range and an IR spectrum. An NMR spectrum was unable to be obtained. The mass of the product was .4162 grams, with a precent yield of 17.34%. The low percent yield can be The melting point range that is expected from 4-cyclohexene-cis-dicarboxylic anhydride is 101-103°C. The actual range that was obtained from the melting point test was 82.9-93.2°C.

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.

The salt lowers the temperature at which water freezes and melts. Pure water, H20, freezes as it melts at, 0°C (32°F). But when salt is increasing, the freezing point is dropped. Salt and water, as different substances, they both carry different chemical properties. Salt gets in the way of the interactions between H and O, making it hard for H and O to bond as ice.

To apply thermal analysis to the two-component system, naphthalene-biphenyl at atmospheric temperature. The analysis will be represented by a solid-liquid phase diagram (freezing point diagram).

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

The objectives of this lab are, as follows; to understand what occurs at the molecular level when a substance melts; to understand the primary purpose of melting point data; to demonstrate the technique for obtaining the melting point of an organic substance; and to explain the effect of impurities on the melting point of a substance. Through the experimentation of three substances, tetracosane, 1-tetradecanol and a mixture of the two, observations can be made in reference to melting point concerning polarity, molecular weight and purity of the substance. When comparing the two substances, it is evident that heavy molecule weight of tetracosane allowed