Experiment 14 - This is a lab report. PDF

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Experiment 14 Immiscible Fluids: Rainbow in a Test Tube Taylor Lee Daniel Kinnaird October 16, 2017 CHEM 1211 Section B01 TA: Jiyao Yu Honor Pledge – Freshman Chemistry Laboratories I did not copy any portion of this work from the work of other students, old lab reports, or unreferenced materials. I understand that such activity is a violation of the Georgia Tech Honor Code. ______________________________________ Signature

Introduction: The Rainbow in a Test Tube lab uses polarity, density, solubility, and miscibility factors to determine the order of six different dye solutions. The goal of the experiment is to create a rainbow of the solutions inside of a test tube. The first important factor to understand about a solution is solubility. A solution is soluble if it completely dissolves in another. The solvent is the solution that is dissolved, while the solute is what does the dissolving. The solvent is the solution present in the greatest amount. The second factor to consider is miscibility, which is the ability of two liquids to mix with each other. If the liquids do not mix, then they are insoluble. Polar solutions are miscible with other polar solutions and non-polar solutions are miscible other nonpolar solutions. However, a polar and a nonpolar solution are immiscible. Polarity is the separation of electric charges that lead to a molecule having a positive and negative pole. Non-polarity is characterized by molecules that have electrons that are distributed symmetrically and have charges that cancel out. A polar solvent is miscible in water, while a nonpolar solvent is immiscible with water. A solution can be mixed with water to determine whether it is polar or nonpolar. Another important factor to consider is the density of a solution, which is determined by the mass of the substance and volume of the substance. Solutions of greater density will sit below solutions that are less dense. In the experiment, the ordering of the layers depends upon the densities of the two immiscible solutions, with the higher density solvent as the lower layer and the lower density solvent as the top layer. The polarity test and the miscibility test must be used together to determine the order of the solutions. The hypothesis for this experiment is that the liquids will settle in order from most dense to least dense, alternating between polar and nonpolar.

Data and Results Solutions EAC DIW FIF LIG DCB HEA

Polarity Non-polar Polar Non-polar Polar Non-polar Polar

Density Test

EAC

HEA HEA is

LIG LIG is

DIW DWI is

FIF

heavier HEA is

heavier LIG is

heaver FIF is

DCB

heavier HEA is

heavier DCB is

heavier DCB is

heavier

heavier

heavier

Each of the six unknown liquids was pipetted into a test tube that was sitting in a test tube tray. A different pipette was used for each liquid in order to prevent cross-contamination. First, each liquid was mixed with water to test its polarity, if the liquid were miscible with water then it was polar and if the liquid was immiscible with water then the liquid was non-polar. For the solutions that were non-polar, the density compared to water was recorded. DCB and FIF were denser than water, while EAC was less dense than water. In order to determine the density of the remaining liquids in relation to each other, the polar and non-polar solutions were mixed to determine density. HEA was mixed with DCB and FIF and was found to be denser than both solutions, therefore HEA was found to be the densest solution and the base of the rainbow. The LIG was mixed with DCB and FIF and was found to be denser than FIF but less dense than

DCB, therefore LIG was the polar solution that fit in between the two non-polar solutions. The order of the solutions, from densest to least dense, was found to be HEA, DCB, LIG, FIF, DIW, and EAC. The polarity, miscibility, and density tests were used together to determine the order of the solutions. The layers of the solutions must be alternating polar and non-polar, in order to prevent the layers from mixing. The layers also must be in the order of most dense to least dense, in order to prevent a denser layer from sinking down to the bottom of the test tube. The order of the solutions was found to be HEA, DCB, LIG, FIF, DIW, and EAC.

Discussion In this experiment, the goal was to consider the density, polarity, and miscibility of six unknown substances, in order to layer the substances to form a rainbow. Each of these factors helps determine the order and layering of the solutions. In order to correctly layer the solutions to create a rainbow, the solutions had to be identified as polar and nonpolar. The polar and nonpolar solutions are layered in an alternating pattern from greatest to least dense. Each solution was

mixed with deionized water, in order to determine if it was polar or non-polar. The polar solutions are miscible with water, while the non-polar solutions are immiscible with water. The two substances that mixed with water were identified as polar and the three that separated were nonpolar. The polar solutions were HEA, LIG, and DIW. The non-polar solutions were EAC, FIF, and DCB. During the polarity test, it was also determined that EAC is less dense than water, FIF is denser than water, and DCB is denser than water. Next, the density of each solution was determined by mixing the non-polar solutions with the polar solutions, allowing the density of the solution to be measured in comparison to the other solutions. In order to do this, the polar and nonpolar solutions were added together to see which one rose and which one sunk. The solution at the bottom was the denier solutions, while the solution at the top was the less dense solution. The order of the solutions, from most dense to least dense, was found to be HEA, DCB, LIG, FIF, DIW, and EAC. Deductive reasoning was used to put the solutions in order after the polarities and relative densities were measured. The order of the rainbow was found by alternating polar and non-polar solutions while considering the order of the density. The order was found to be HEA, DCB, LIG, FIF, DIW, and EAC. Once the order was concluded, dyes were added to each solution to make them into a rainbow. The experiment is considered successful because the solutions were able to form a rainbow without mixing together. The hypothesis for this experiment is that the liquids will settle in order from most dense to least dense, alternating between polar and nonpolar. The evidence found in this experiment supports this hypothesis. The errors in the experiment could come from a lack of precise measurements and calculations. The density of each liquid could have been determined by dividing the mass of the liquid by the volume of the liquid. This technique could have provided a more accurate and reliable set of data. Another error that could

have occurred is cross contamination. My ground labeled each test tube and pipette in order to prevent cross-contamination because it could cause errors in the results.

References Bottomley, L.; Bottomley, L.A.; CHEM 1211K/1212K, Chemical Principles I & II Laboratory Manual, 2015-2016, p. 120-123...