I had a chromatography experiment for chemistry and here is one of the questions:
Did the compounds travel farther in the water or the isopropyl alcohol (rubbing alcohol)? Explain why you think that this is the case.
Now, the compounds traveled the farthest in the water but I don't know why (I used crayola markers). I thought it would be the alcohol because of the fumes. I'm trying to research about it but I'm not getting anything. Can somebody help me with an explanation for this?
But so far, what I have is that since Crayola markers use mostly dye and WATER, maybe the water molecules had absorbed into the paper a lot easier.
This could be totally wrong:/
I assume from the last part of your post that you are using paper chromatography. If so,the paper is the stationary phase and the solvent is the mobile phase. Compounds that are very soluble in the mobile phase (in this case I think you used different solvent), they will move up the paper farther than compounds that are not very soluble. You can Google paper chromatography and read more about it there.
Your initial thoughts about the compounds traveling farther in alcohol due to its fumes are understandable. However, let's delve into the possible reasons why the compounds actually traveled farther in water rather than isopropyl alcohol.
1. Solubility: The first factor to consider is the solubility of the compounds in the solvent. In this case, since the markers are water-based, the dyes used in the markers would be highly soluble in water. The water would effectively dissolve the dyes and allow them to migrate easily along the chromatography paper. On the other hand, the polarity of the dyes may not be compatible with the nonpolar nature of isopropyl alcohol, thus limiting their solubility and the distance they can travel.
2. Capillary action: Another explanation can be attributed to capillary action. Water has a high surface tension and exhibits capillary action, meaning it can move against gravity through narrow spaces, such as the fibers in the chromatography paper. This capillary action helps to facilitate the movement of the compounds up the paper, allowing them to travel a greater distance. Isopropyl alcohol, although it also exhibits some capillary action, may have a weaker capillary effect compared to water, resulting in shorter migration distances for the compounds.
3. Absorption by paper fibers: As you mentioned in your initial thought, the water molecules may have absorbed more easily into the paper fibers due to the paper's hydrophilic nature. This absorption would allow the water to carry the dyes along as it is drawn up the paper, enabling the compounds to travel farther. Isopropyl alcohol, being less polar, may not be as readily absorbed by the paper fibers, limiting the distance the compounds can migrate.
In summary, the compounds in the Crayola markers likely migrated farther in water compared to isopropyl alcohol due to the markers' water-based composition, solubility of the dyes in water, capillary action, and absorption by the paper fibers. These factors contribute to the compounds' ability to move more easily and cover a greater distance in the water solvent.
Your initial intuition that the compounds would travel farther in the isopropyl alcohol (rubbing alcohol) due to its fumes is reasonable, but in this case, the compounds traveled farther in water. The reason for this can be explained by the principle of solubility.
In chromatography, two substances play a crucial role: the mobile phase and the stationary phase. The mobile phase is the liquid or gas that carries the compounds you are analyzing, and the stationary phase is the medium through which the compounds move. In this case, the mobile phase is the water or the isopropyl alcohol, and the stationary phase consists of the paper chromatography strip.
The key factor that influences the movement of the compounds is their solubility in the mobile phase. Solubility refers to how well a substance can dissolve in a particular solvent. Different compounds have different solubilities in different solvents.
The Crayola markers you used primarily contain dyes that are water-soluble rather than alcohol-soluble. Therefore, when you added water to your experiment, the water molecules acted as the mobile phase and readily dissolved the water-soluble dyes in the markers. These dissolved dyes were then able to travel easily along the paper strip.
On the other hand, isopropyl alcohol is less effective at dissolving the water-soluble dyes in the markers. While there may be some solubility and movement in isopropyl alcohol, it is not as efficient as in water.
In summary, the compounds in the Crayola markers traveled farther in the water because the dyes present in the markers are primarily water-soluble. The water molecules readily absorbed and dissolved these dyes, allowing them to move more easily along the paper chromatography strip.