1. Determine the hypothesis of the following procedure 2. Which substance is the

Question

1. Determine the hypothesis of the following procedure

2. Which substance is the organic layer and what will the organic layer dissolve and which part is the aqueous layer and where will the neutral part dissolve in according to the following procedure?

You will be given an unknown mixture containing equal parts by mass of an organic acid and a neutral compound. You will take advantage of acid-base extraction to separate your compounds. You will identify the components of your mixture based on melting point ranges.

Dissolve 1.2 g of unknown in 12 mL of tert-butyl methyl ether (remember to record your unknown number as well as to accurately record the exact mass of unknown used) in a clean 50 mL Erlenmeyer flask. Transfer the solution to a 50 mL separatory funnel and add 6 mL of 1 M NaOH. Mix the contents gently; let the layers separate. Remove the aqueous layer and place in a 50 mL Erlenmeyer flask labeled flask A. Now add another 6 mL of 1 M NaOH to the separatory funnel. Mix contents gently; let layers separate. Remove the aqueous layer and add it to your flask labeled A.

To the contents in the flask labeled A, add 4 mL of 3 M HCl. Stir the suspension. To maximize yield of organic acid, make sure the system is strongly acidic by checking the pH using wide range pH paper. Add HCl until a strongly acidic solution is obtained. Place the Erlenmeyer in an ice water bath and stir occasionally for 15 minutes. Collect the product by vacuum filtration. Place the product on tared watch glass and dry in an oven maintained at 80 oC. Determine the crude melting point of your material as well as the crude weight of your material. Recrystallize if necessary.

To the organic layer in the separatory funnel, add 5 mL of saturated NaCl. Mix the contents gently; let the layers separate. Remove the aqueous layer and place in a 50 mL Erlenmeyer flask labeled B. Pour the ether layer out of the top of the funnel into a 50 mL Erlenmeyer flask labeled C. Dry the ether layer with a small amount of anhydrous Magnesium Sulfate. Separate the Magnesium sulfate by gravity filtration using a Pasteur pipet as the funnel and a Kimwipe as the filter paper. Place the ether layer in a clean, dry, tared 50 mL Erlenmeyer. Evaporate the ether in the hot water bath in the hood. Determine the amount recovered as well as the melting point of the neutral solid.

Explanation / Answer

1. Hypothesis of the procedure is that like dissolves like. This means that a polar solvent like water will dissolve polar (ionic) compound. whereas, non-polar (neutral) compounds are dissolved in non -polar solvent like diethylether.

2. The organic layer substance is tert-butyl methyl ether. NaOh part is the aqueous layer. Neutral compound is in organic layer and organic acid is in the aqueous layer.

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