Spinach Leaves Essays

In this investigation, a TLC plate and ethyl acetate (solvent) were used to measure the Rf values of four different solutions of Tylenol, Anacin, Acetaminophen, and Acetylsalicylic acid. The value of Rf depends on the strength of the intermolecular forces that exists in molecules. The stronger the intermolecular forces are, the harder the solvent moves the molecule up, resulting a small Rf value. In contrast, molecules with weak intermolecular forces tend to have a high Rf value.

rate compared to the actual diffusion rate? Yes, because the rate of diffusion is faster until the equilibrium is reached; after equilibrium the rate of diffusion begins to decrease.

Adsorption chromatography occurs when “one substance form[s] some sort of bonds to the surface of another one”, creating intermolecular forces between the two substances (Chemguide). For thin layer chromatography, the components of the mixture are adsorbed onto the stationary phase that covers the plate (Chemguide). The more polar a substance is, the more strongly adsorbed it is (Chemguide) and the strong intermolecular forces then result in a slower rate of migration with respect to the moving phase. As the solvent touches the TLC plate, the solute (mixture) is allowed to move up the TLC plate

Other information that can be obtained from a TLC analysis is the progress of a chemical reaction, which can be done by taking samples from the reaction mixture at various intervals and spotting them on TLC plates and taking down the Rf factor. Also TLC analysis can be used to determine the optimum conditions required to obtain a high yield of the desired product with little to no side products. Yield can be ascertained via TLC analysis in that the reactant and product intensity on the TLC plate will have varying degrees of intensity. At the end of the reaction, the product should have the most intensity, while the reactant has the least intensity. At the beginning of the reaction, it would be the other way around. With this, you can determine the percent yield of the

1. What was the purpose of using water as a sample in some of the tests performed in the lab? (2 points) to have a control.

Substance A and B were weighed; Substance A weighed 0.502 g and substance B weighed 0.503 g. Both substances were put into two different test tube with approximately 8 ml of DI water into the test tub. Substance A and B were stirred and B dissolved while A did not. This shows that B is soluble in water compared to A. Thus, shows that B is soluble in water than A. The reason why B is soluble in water is because it has a higher dipole moment than A. With a higher dipole moment, it shows that it is soluble in water since it is polar and the bonds were easily broken.

The materials needed for this experiment included test tubes, a test tube holder, the unknown compound #202, 35mL beakers, gloves, safety goggles, ethanol (to clean equipment), stirrer (to mix solutions), the 15 possible compounds that are provided, pH strips, distilled water, wooden splints, spatula to get out unknown compound #202, waste bucket, Bunsen burner, graduated cylinder, 500mL beaker for the waste, plastic dishes to measure out compound and the scale.

The eluting solvent passed down the column by the gravity and an equilibrium was established between the solute absorbed by the absorbent (silica gel in this experiment) and the eluting solving flowing down. Since the components in the sample had different polarity and they interacted with the stationary phase and the mobile phase differently, the components would be carried by the solvent to a different extent and a separation of the components could be achieved.

In the extraction of certain compounds, solubility plays an important factor in how the procedure is performed. The identification of which solvent is best for the substance is crucial. The relation of polarity between the solute and solvent is determined at a molecular level. The relationship between the solvent and solute needed shared similar characteristics. Polar solutes are dissolved in polar solvents while nonpolar solutes are dissolved in nonpolar solvents. From a chemical level, molecules are attracted to other similar molecules closest to their properties. Polar molecules are only attracted to polar molecules in both the solute and the solvent, and the same goes for nonpolar molecules. This explanation

Pigments extracted from different greens have different polarities and may be different colors. Mixed pigments can be separated using chromatography paper. Chromatography paper is able to separate mixed pigments due to their polarity and solubility. Pigments of chlorophyll a, chlorophyll b and beta carotene will be separated on chromatography paper because each has its own polarity and solubility, which results in different distance traveled up the paper. Beta carotene is non-polar so it travels the highest distance, followed by chlorophyll a. Chlorophyll b is the most polar; therefore, it travels the shortest distance. The separated pigments on the chromatography paper can be eluted in acetone and absorbance spectrum is

     In liquid chromatography, the separator is called the column and consists in most cases of a tube filled with porous material called the stationary phase. A liquid, called the mobile phase, flows through the tube between the particles of stationary phase material. A liquid sample is taken from a mixture to be analyzed and introduced to a part of the system that is at elevated pressure. The sample is then transported to a separator by the flow in the system.

The “E” solution ended up having the most spots because it was the pigment fragments. The Rf values could be calculated for all of the spots by taking the distance traveled by the spot and dividing it by the total distance traveled by the solvent front. The calculations are as shown:

After wearing the gloves we obtained a chromatography vial from professor and label it with my and my peer initials. We dried up the chromatography vial in fume hood and added 1 ml of chromatography solvent to the vial. Then we took a chromatography strip and measure it 1.5 cm with ruler from one end of the strip and drew a line with pencil we cut two small pieces below the pencil line to form a pointed end. We applied spinach on the strip using quarter to rub the spinach leaf on the line that we drew on the strip and put it into the chromatography vial and placed that in fume hood. We observed as the solvent was moving up the chromatography strip by capillary action. When the solvent was reached approximately 1 cm from the top of the strip then we removed the cap from the vial. We took out the strip from the vial using forceps and marked up the location of the solvent front because it evaporates quickly. We measure out the distance as well as the pigment in order to find out the rf value. Moreover we compared rf values to the one in reference list in order to identify the

The purpose of this lab was to study colligative properties. These properties are properties that are affected when a solute is added to a solvent. Thus, the amount is important, not the actual type of substance, for the colligative properties. A couple types of this property are the freezing point and boiling point of a substance. (1)

Gel-Filtration Chromatography is a commonly used method used in order purify a protein from a mixture, by means of separations. Different biomolecules differ in size, or their molecular weight. In the gel matrix inside the chromatography column, there are gel beads which are porous to allow certain sized molecules to enter. The molecules that are able to enter the pores of the gel, are held in stationary phase and will elute from the column later on, these are usually smaller, to medium sized molecules. Larger molecules that are not able to fit in the pores will elute out of the column first, they are involved in mobile phase where they just go straight through the column without interacting with the gel beads. Smaller molecules will have a higher elution volume, while the larger molecules will have a lower elution volume. The volume to elute the protein is inversely proportional to the molecules size.