Determining the Identity of Unknown Substances by using the Rƒ Factor found with Chromatography Paper
Purpose
To separate molecules that are attracted to one another using the principles of intermolecular forces as well as a scientific ratio to find the identity of unknown substances.
Theoretical Background
Chromatography corresponds to the solubility of substances in a mixture, as well as, its ability to separate in different solvents. The level of separation is measured by a relative amount, Rƒ, which compares the distance that the molecule travels to the distance the solvent travels. This ratio can be calculated by the equation:
Rf=D/L=(distance solute moves)/(distance solvent moves)
Pre-Lab Work
How can molecules attract each other when they are in a mixture? Predict how ethanol would interact with those molecules. Draw a picture illustrating the interactions between the components of the mixture and the solvent, ethanol.
Molecules attract one another’s opposite partial pole due to London dispersion and Coulomb force. Substances in a mixture are not chemically bonded. There are four types of intermolecular bonds with ethanol which are London dispersion, dipole-dipole, covalent, and hydrogen. Ethanol will interact with water and bond producing a tightly bonded mixture, where as vegetable oil does not mix with water molecules. Theses structures are depicted in the figure below:
What does the Rƒ value describe on a microscopic level? Why is this important?
On a microscopic level the Rƒ value. This is important because it is used to determine the identity of substances and its solubility in various solvents. Also, the Rƒ value affects
If the molecule has a very high affinity for the stationary phase...
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...chromatography worked. Explain your picture using the following terms: stationary phase, mobile phase, solubility and intermolecular forces.
In the stationary phase (the paper), each substance is in its original mixture. The mobile phase (the solvent), is what transports the molecules up the chromatography paper. This assessment allows one to test the solubility of given substances depending on the intermolecular forces, those whose bonds are more weak travels through the mobile phase more quickly than that of those whose bonds are more tight and less soluble.
Which molecule spent the most time in the stationary phase and why?
Bromythmol blue spent the most time in the stationary phase because it is the more polar and molecules with more polarity take more time to dissolve on the solvent and rise through the cellulose fibers of the chromatography paper.
Introduction: Someone in a restaurant has suddenly fallen ill and a mystery powder has been discovered with the victim. As the chief investigator, your duty is to identify the mystery substance through a lab. In this lab, it will consist of five known compounds and one unknown compound. Your job is to distinguish which one out of the five substances is the mystery powder. To figure out the mystery matter you will have to compare their physical and chemical properties and match them with the appropriate compound. Furthermore, you will compare their reactions with water, universal indicator, vinegar and iodine solution to discover what the mystery powder is.
The absorbance of these mixtures is measured at a suitable wavelength. If 'x' mole/litre are added to (1-x) mole/litre of M and if C1, C2
Afterwards, we conducted crystallization to evaporate the liquid in an attempt to detect the presence of a salt. Before stating which of the potential
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Adding the sample to chromatography column uses a careful technique. The solvent should be added so that it is just below the top of the packed column. With the stopcock closed and after the stopper is removed at the stop of the column and the clamp on the tubing at the top of the column is closed, the sample solution can be added carefully. The clamp on the tubing is opened so that the sample can go through the column until it is right below the top of the column. The packed column should not be disturbed as the sample is poured in. Once the clamp is closed again, a little bit of solvent is added. The clamp is opened so that the solvent can run through, and then again the clamp is closed and more solvent is
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As explained by Saferstein “Chromatography is a means of separating and tentatively identifying the components of a mixtur... ... middle of paper ... ... ively place the suspect or perpetrator behind bars. Analyzing soil compounds can be measured by the levels of organic molecules including n-alkanes, fatty alcohols and fatty acids, which are all found in the waxy outer layer of plant matter (Geddes, 2008). It basically states that compounds can remain in the soil for thousands of years, which explains that each area being tested has its unique organic profile.
They are usually made up of surfactants, which are surface active agents which reduce the surface tension of water by absorbing the common boundary between more than one liquid (3). The amphipathic character of detergents is evident in their structures, which consist of a polar (or charged) head group and a hydrophobic tail. Depending on the head of the detergent they can either be ionic, nonionic, and zwitterionic. This is dependent on the stereochemistry of the entire detergent. Detergent monomers self-associate to form structures called micelles. When the concentration exceeds the CMC, a detergent becomes capable of solubilizing hydrophobic and amphipathic molecules, such as lipids, into mixed micelles or micellar aggregates( ). In micelles, the amphiphilic lipid has a tail that forms a core that encapsulates an oil droplet or dirt particle and a head that maintains contact with the surrounding water environment. To work effectively, the chemical formation of micelles is not enough to remove oil or grease; mechanical energy (scrubbing or water flow) is often required
By doing this experiment, I can know the physical and chemical properties of these samples. After I get my results about the physical and chemical properties of these samples, I can compare my results with the information given by the past student and identify the 5 unknown samples, finding out which sample is which substance. Hypothesis = ==
Water molecules are polar, with negative charge on the hydroxyl ions and positive charge on hydrogen ions. The attraction of oppositely charged poles of water molecules cause them to group together. Attractive forces form hydrogen bonds. The substances that are able to dissolve in water are known as hydrophilic substances. Water can be used as temperature stabiliser.
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