TLC Experiment

Both Aspirin and the Unknown are soluble in dichloromethane, due to their non-polar characteristics. To separate the two components, sodium bicarbonate was added (see figure 3). Sodium bicarbonate reacted with aspirin and converted it to a salt, also forming water and carbon dioxide. It was observed that the solution "fizzed" when this reaction took place, showing the release of carbon dioxide. The newly formed salt then traveled to an aqueous layer where it was soluble, while the unknown remained in the dichloromethane layer. The two layers were then separated. To collect an aspirin solid, the combination of the addition of HCl and the process of vacuum filtration helped to break down the salt and form a solid. Then the solid was placed in the Fisher Scientific Biotemp Oven to dry it to a constant mass of 0.091 g, 32.97% of the total composition. The

Prior to beginning the experiment, it is important to understand a few different concepts such as the distinguishing physical properties of a chemical substance and how these physical properties can be analyzed. Physical properties of a chemical substance include water solubility and melting point, both of which are used to pursue identification of the unknown component of Panacetin. Water solubility is a distinct physical feature of chemical substances that can lead to an increase or decrease in product recovered. For example, the water solubility of the two possible unknowns, acetanilide or phenacetin, are different in opposite temperature spectrums. Acetanilide’s cold water solubility is 0.54 grams/100 mL of water, whereas the substance’s boiling water solubility is 5.0 grams/100 mL of water.

It is also important that the proper solvent does dissolve impurities at room temperature but does not dissolve impurities near its boiling point. 7) Thin-layer Chromatography (TLC) was used in the experiment to identify the filtrate. TLC works by applying a sample of the filtrate onto a TLC plate that is partially submerged in a solvent in a closed jar. The filtrate then moves up the plate through capillary action, and the distance that the filtrate moved (the Rf value) is measured. This value is then compared to Rf values measured from given solutions, and the filtrate is identified by matching its Rf to the closest Rf of a given

The first TLC plate showed that the fractions collected during the experiment that appeared to be the purest were fractions 4 and 6. These two fractions and fractions number 5 were combined for the final product. The Rf values for the standard carvone, fraction 4, and fraction 6 were all 0.32 indicating that these compounds were

In the first part, there may have been cross contamination of materials, especially since periods before us had already performed the experiment. During chromatography, our spot sizes were initially very varied, as we didn’t know exactly how much of each substance to place when we began. Thus, the substances in more abundance would have greater opportunity to travel up with the eluent, skewing the results. In the beginning, we even put 6-7 drops, causing some of the substances to mix together. Touching the TLC plate may also have disrupted some of the substances traveling up.

1. Which solvent or solvent mixture did you decide to use for your TLC? Why?

During the qualitative solubility test, the unknown substance dissolved in water. This means that the substance is a polar or ionic compound4. Calcium Chloride is an ionic compound. The substance also dissolved in Acetone which is typical of Calcium Chloride2. The quantitative solubility of the unknown substance averaged to 188 g/L. The known value for Calcium Chloride is 745 g/L1. These differences in values could be due to the amount of solute used being small, making it difficult to measure the change in volumes. Also, accuracy of the balance could play a part in skewing the

The TLC plate is sprayed with about 10 ml, heated at 1000C for 5-10 min, and then evaluated in vis. or UV-365nm. The reagent has only inadequate strength and is no longer useable at what time the colour has

1. Why did you select the solvents that you tested? Did your data support your hypothesis or disprove your hypothesis? We selected water because it is a constant and it is a common solvent, as well as we selected acetone and ethanol, since all three of these solvents are very different from each other, such as their structure and polarity levels.

The purpose of using solubility analysis on an unknown is to narrow the possible unknowns given based on the solubility analysis. Acetone was a control for ketone and was soluble in water. Hexanal was a control for an aldehyde and was insoluble in water due to intermolecular forces, such as an increased amount of hydrophobic area rather than hydrophilic area. As a result, by identifying the solubility of the

Once the solvent line has risen, the plate was removed and allowed to dry, and the solvent line marked. Once the TLC plate was dried, it was analyzed under a UV Light and circles placed around visible spots where the solutions had traveled (Figure 3). The Rf values were calculated, Table 3, by using the measured distance the spot

Discussion As part of the experiment, the percent composition of each component of the mixture was calculated. 51% of the components were retrieved from filtration while 49% of the solvents were retrieved from dissolving the components in a solvent. The original mixture was one globular solid-like structure.

The amount of tablets did effect the temperature of the water. Our findings made our hypothesis incorrect. The temperature of the water did increase as the number of the tablets increased also. In this experiment, the finding were quite surprising, simply because I thought that the temperature of the water will decrease as the amount of the number of tablets increased. In the real world I feel like this information would be beneficial, because it shows the reaction of an acid plus a base mixed with water.

The products that were made in each reaction, the oxone and the potassium permanganate, were used as samples for the TLC plate. The lane 4 sample, oxone, was exactly similar to the actual trans-1, 2-cyclohexandiol-sample test. Lane 5, the potassium permanganate sample, was exactly similar to lanes 1 and 3 of cis-1, 2-cyclohexandiol. Lane 3, that had supposedly a mix containing cis-1, 2-cyclohexandiol as well as trans-1, 2-cyclohexandiol had only come out with a blob that compared to the cis-1, 2-cyclohexandiol. The trans-1, 2-cyclohexandiol sample never showed up in that lane, possibly due to the fact that maybe no sample was placed or maybe a super tiny sample that was undetectable had been spotted so no results showed

The TLC experiment helps you find each individual element inside a mixture. It helps to isolate the chemicals in a solution so you can find its identity. For example it can used identify different amino acids from a protein and test on them. It is also used to identify unknown substances in a mixture. It can also identify how much of each substance there is inside the mixture. If the compound is soluble in the solvent it means it will move quicker.