On the left is my lab instructions,thr right the table for 1a and the bottom the
ID: 884828 • Letter: O
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On the left is my lab instructions,thr right the table for 1a and the bottom the rest of 1. Volume of methanol is 2ml but not sure how to calculate the rest. After heating the test tube for methanol weighed 6.59 grams and the one for hexane weighed about 7.70 grams. I don't know how much the test tube by itself weighs but I think for now I can estimate it to be around 6 grams. How do I use this info to figure out how to fill out the table and 1b,c,d . Please and thank you!
Search Solvent Top Layer Hexane CIS Experiment-your instructor will demonstrate this technique with you: I will dissolve 1. Test the miscibility of the two solvents. Add 4 drops ofto a reaction tube. Add 4 drops of What did you observe? g of benzoic acid in ml of Then, I will add ml of to extract the benzoic aci to the cre 2. a. Add 0.03 g of benzoic acid to a second reaction tube. Add (water or hexane) until all of the benzoic acid dissolves What volume of (water or hexane) did you add? Does this volume match the solubility of benzoic acid in Table 3 or Table 6? 0 Solvent- Bottom Layer Methanol b. Add 2 ml of (diethyl ether or methanol) to the benzoic acid solution Did you see 2 layers form? The top layer is Mass of Benzoic Acid dissolved in (water or03g because of the property of hexane),g c. Mix the 2 layers by gently flicking the test tube with your finger several times For what reason do you need to mix? Volume of (water or hexane) to dissolve 4.65 mL benzoic acid, ml Volume of (diethyl ether or methanol), ml Mass of benzoic acid in (water or hexane) cre d. Separate the layers by using a Pasteur pipet to remove the lower layer. Place the lower layer in another test tube The lower layer contains layer after extraction, g 3. We want to determine if any benzoic acid was extracted from the (water or hexane) to the (diethyl ether or metha a. In the hood, remove the How will you do this? from the top layer Mass of benzoic acid in (diethyl ether or methanol) layer after extraction ,g Dry any solid that remains. Measure the mass of the dry solid. % of benzoic acid extracted to (diethyl ether or met he from the bottom layer. b. In the hood, remove t How will you do this? Repo 1. a. Show your Table 7. b. Explain why hexane is not soluble in methanol c. Did you remove all of the benzoic acid from thein one extraction? Would you expect the distribution coefficient of Dry any solid that remains. Measure the mass of the dry solid c. Record your data in Table 7. to be large or small? Give reasons. d. In general, how many times should an extraction be repeated to remove as much of the desired substance as possible?Explanation / Answer
1. a. Table 7.
Solvent top layer = Hexane
Solvent bottom layer = Methanol
Mass of benzoic acid in water or hexane = 0.03 g
Volume of water or hexane to dissolve benzoic acid = 4.65 mL
Volume of diethylether or methanol = 2 mL
Mass of benzoic acid in diethylether or methanol layer after extraction = 0.03 - x
where,
Kd is distribution coefficient of benzoic acid in diethylether and water = 10 [from literature]
x = amount remaining in water or hexane
Distribution coefficient = 10 = [(0.03 - x)/2 mL]/(x/4.65 mL)
Solve for x,
x = 0.00566 g
Thus, mass of benzoic acid in diethylether or methanol after extraction = 0.03 - x = 0.0243 g
% of benzoic acid extracted in diethylether or methanol = 0.0243 x 100 / 0.3 = 81.0%
b. Hexane is a non-polar hydrocarbon solvent, whereas, methanol is a polar solvent. In solubility we have to remember that like-dissolves-like. Thus a non-polar solvent or solute will be more soluble in a non-polar solvent, whereas, a polar solvent or solute would be more soluble in a polar solvent. Thus, hexane is not miscible with methanol.
c. In the extraction process it is not possible to remove all the solute in one extraction. Multiple extractions are required to extract the complete solute dissolved in a mixture of two immiscible solvent mixture.
Thus, we did not remove all of the benzoic acid from the water/hexane layer in one extraction. The distribution coefficient (D) which is the ratio of solute dissolved in the mixture of two immiscible solvent mixture is expected to be high in this case. Benzoic acid is more soluble in methanol as compared to water or hexane.
D = amount of benzoic acid in dissolved in methanol / amount of benzoic acid dissolved in water or hexane
c. In general a minimum of three extractions (can be higher depending on the solubility of the solute in the two solvents) are adviced to remove as much of the desired substance as possible.
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