Lab report 3 : Extraction PDF

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Lab report 3 on Extraction...

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Huynh 1 Tam Huynh Professor Dutz. CHEML220 March 2, 2020 Lab report 3: Extraction. Lab partner: Jovan. Discussion. Part A. For every trial that we used, if the unknown does not appear on ether layer as precipitate, it should appear in the aqueous solution as precipitate. This happens because if the unknown does not react with any solution, it will remain on the ether layer as precipitate when it is heated up. In contrast, if the unknown reacts with any solution, it will remain in the aqueous solution and precipitating as it is heated up. For Benzoic Acid, among data collected for 3 trials of this Acid functional group, the only precipitate that was found in aqueous layer should only be in 1M NaOH trial. Because Benzoic Acid will react with NaOH; therefore, it will stay in NaOH aqueous layer and precipitate out when heating up instead of ether layer. For Ethyl paminobenzoate, the only precipitate that was found in aqueous layer should only be 1M HCl. Because Ethyl p-aminobenzoate has an amine that acts as a base functional group, which will react with strong acid HCl. Therefore, it remained in HCl aqueous layer and precipitate out when heating up instead of ether layer. Last is Benzophenone, because this substance would not react with any aqueous solution and is insoluble in water, it will remain only in ether layer and precipitate out when heating up for all 3 trials in 3 aqueous solution. In conclusion, if precipitate was found in 1M NaOH aqueous layer, it should be Benzoic Acid. If precipitate was found in 1M HCl aqueous layer, it should be Ethyl p-aminobenzoate. If precipitate was not found in any aqueous layers but in ether layers, it should be Benzophenone. Therefore, the identity of unknown with their number is that:

Huynh 2 + Unknown 13: Benzoic Acid + Unknown 18, 15, 8, 12: Benzophenone + Unknown 17, 14, 11: Ethyl p-aminobenzoate. Balanced chemical equations:

Part B. Extraction Benzophenone + Ethyl p-aminobenzoate Flow chart showing the separation scheme, including the chemical species present (as structure) at each step in each solution.

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The recovery mass of each compound should not be bigger than 0.535g (since the initial mass is 1.070g) because of the ratio 50:50 mixture. During the extraction process, there must be source of loss for both compounds. First is when the venting separatory funnel was performed, there was a few drops of solution fallen out when flipping the separatory funnel to mix the mixture (15mL of ether and 10mL of 1.0M HCl). Second, when removing the lower layer to receive the ethyl p-aminobenzoate in HCl aqueous solution, the stopper technique was not done right by stopping it a bit late; therefore, the mixture of ether and benzophenone could be lost. The transferring process of ether solution to 25mL Erlenmeyer Flask could be a source of loss since the solution could still stay in the separatory funnel. For the Erlenmeyer Flask of aqueous solution, when the solution precipitated out, the transferring process from the Buchner funnel to the 50mL Erlenmeyer Flask to the Buchner funnel could be a big loss for the ppt. Even the remaining ppt that stayed in the flask was rinsed with ice water, there was still some residue left

Huynh 4 in the flask, which could cause a big loss for the ppt mass. After this step, when the ppt was dried and transferred to the watch glass to weight, ppt once again stitched on the Buchner funnel or fallen outside, which once again cause a big loss for ppt mass. Calculating Recovery mass:

The melting point range that was measured for Benzophenone is 48.2ºC - 49.3ºC, for Ethyl p-aminobenzoate range is 91.1ºC – 92.1ºC. Comparing to the original melting point data

Huynh 5 that was given for the 2 compounds, the melting point range of these 2 compounds are almost the same as the given data: Benzophenone data given range: 48 -50ºC comparing to Benzophenone measured range: 48.2ºC - 49.3ºC, Ethyl p-aminobenzoate data given range: 91-92ºC comparing to Ethyl p-aminobenzoate measured range: 91.1ºC – 92.1ºC. Because the melting point range measured itself is close to each other (within 2ºC), and close to the value of the given data, it could imply that the purity of the final compounds is good extracted and pure. It also means that the extraction was success and each of the compounds has completely extracted from other with no impurity materials. Post – Lab questions: 1. The method that was devised for part B cannot separate a mixture of two amines. Because two amines will have same functional group, which will do the same function when react with HCl (since amine has a base character). Therefore, if the two amines are put into the separatory funnel with ether and 1M HCl, the two will react with HCl and stay in the aqueous solution. Therefore, it will be no ppt in the ether layer, instead, the ppt will appear in HCl aqueous solution, but the ppt belong to both 2 amines. So, the extraction fail since the method cannot separate the mixture. 2. A flowchart to show how a mixture of benzoic acid, ethyl p-aminobenzoate, and benzophenone are separated.

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3. Based on the data from Experiment 1 (part C) for the solubility of ethyl alcohol in water. Extraction could not be used to separate benzoic acid from the ethyl alcohol it is dissolved in. Because ethyl alcohol has Hydrogen bonds, which will bond with Hydrogen bonds of water molecules; therefore, ethyl alcohol is very soluble in water. For extraction method, the experiment needs 2 solution that is not miscible so that the 2 layers in the separatory funnel will appear for extraction. Else, the extraction will fail because the substances that are put in the separatory funnel cannot separate out from each other (which will happen similar with question number 1). If there is no separation, there is no extraction happens....