Expt 4A Partition Coefficient Part A PDF

Preview

Summary

lab report for experiment 4 A...

Description

Kelly Guerriero Section 4 TA: Femil Shajan

Lab performed: 8/31/20 Report due: 9/7/20

Experiment 4A: Partition Coefficient Part A Objective The purpose of this lab will be to use lab skills such as, using the electronic balance, automatic delivery pipets, a Pasteur filter pipet, and a Vortex mixer to determine the partition coefficient of 9-Fluorenone at the microscale level. Experimental Procedure The procedure was followed as described in Mayo, pages 144-145, with the modifications listed in the posted Canvas document. Additional modifications include:  Using 9-Fluorenone instead of benzoic acid  Using 75 mg of 9-Fluorenone and 1.0 mL each of methylene chloride and water during the initial addition  Transfer of the methylene chloride layer will be done using a simple glass pipet, instead of a filter pipet. The solution will be transferred to a test tube instead of a 5 mL conical vial. Anhydrous sodium sulfate will be used instead of magnesium sulfate  The remove the sodium sulfate, you will filter the methylene chloride through a glass pipet with a small ball of cotton collecting the dried liquid in a screw cap tube. You will use a heater block to concentrate the final dried methylene chloride solution. Add a boiling stone and a tag with your name to your screw cap tube before obtaining the tared weight. Reaction Scheme Chemical structure of 9-Fluorenone

Data and Results Mol. Formula Amount (mg) Amount (mL) mmoles Molar Mass Density (g/mL) mp (C)

9-Fluorenone C13H8O 70 2.6 180.20 0.93 80-83

Methylene Chloride CH2Cl2

Water H 2O

1.00

1.00

1.33

1.00

bp (C)

163-166

40

9-Fluorenone used Final weight of vial & boiling stone & solid Weight of vial & boiling stone

100

70 mg 4.585 g 4.526 g

Observations  After adding the 9-Fluorenone to the water and methylene chloride, the methylene chloride layer, the bottom layer, turned a yellow/green color. Calculations  9-Fluorenone in CH2Cl2 = (final weight of vial & boiling stone & solid) – (weight of vial & boiling stone) o 9-Fluorenone in CH2Cl2 = 4.585 g – 4.526 g o 9-Fluorenone in CH2Cl2= 0.059 g = 59 mg  9-Fluorenone remaining in aqueous layer= (original mass of 9-Fluorenone) – (9Fluorenone in methylene chloride) o 9-Fluorenone in aqueous layer = 70 mg – 59 mg o 9-Fluorenone in aqueous layer = 11 mg = 0.011 g  To find the partition coefficient, you can use the following formula: 9-Fluorenone Kp = CH2Cl2 / H2O 9-Fluorenone Kp = 0.059 g / 0.011 g = 5.36 Questions 1a.

Non-polar regions

1b. London dispersion 1c. Polar region

1d. hydrogen bonding, dipole-dipole, dipole-induced dipole, London dispersion 1e. 9-Fluorenone will be more soluble in methylene chloride because it is a more non-polar organic solvent. Like dissolves like, meaning non-polar solvents dissolve non-polar solutes. 1f. Yes, since the partition coefficient was greater than 1 (5.26) that supports the fact that mostly all of the 9-Fluorenone dissolved in the methylene chloride. 2a. Ethylene chloride would form the bottom layer. 2b. Ethylene chloride would form the bottom layer because it is more dense than water. The density of ethylene chloride is 1.26 g/mL and the density of water is 1.00 g/mL. 2c. Methylene chloride is superior to ethylene chloride as an extraction solvent because the boiling point of methylene chloride (40 C) is much lower than the boiling point of ethylene chloride (83 C), making it much easier to be removed when being heated.

Works Cited: 1.May o,D.W. ;Pi k e,R.M. ;For bes ,D.C.Microscale Organic Laboratory with Multistep th and Multiscale Syntheses, 5 ed.; John Wiley & Sons, Inc., 2011; pp 141-145. 2. Modifications for Expts 4A: Partition Coefficient Part A, Canvas document....