Acid Base - Report

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Western Kentucky University *

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222

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Chemistry

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Feb 20, 2024

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Name: _____________________________________________________________ ACID-BASE EXTRACTIONS CHEM 341 Table of physical constants (5 points): (tabulate name, structure, molar mass, density (liquids only), melting point, boiling point, and safety hazards for all chemicals mentioned in the procedure) Name and Structure Molar Mass (g/mol) Density (Liquids Only) (g/mL at 25°C) Melting Point (°C) Boiling Point (°C) Safety Hazards Diethyl Ether 74.12 g/mol 0.706 -116.3 34.6 can cause drowsiness, excitement, dizziness, vomiting, irregular breathing, and increased saliva. High exposure can cause unconsciousness and even death. Diethyl Ether is a HIGHLY FLAMMABLE LIQUID and a DANGEROUS FIRE HAZARD. Hydrochloric Acid 36.458 1.2 -26 -110 Hydrochloric acid is corrosive to the eyes, skin, and mucous membranes. Acute (short-term) inhalation exposure may cause eye, nose, and respiratory tract irritation and inflammation and pulmonary edema in humans Benzoic Acid 122.12 1.27 122.3 249.2 Eye damage, Irritation of the skin, resulting in a rash, redness, and/or a burning feeling. Irritation to the nose, throat and lungs if inhaled, which may cause coughing, wheezing and/or shortness of breath. Naphthalene 128.17 1.02 80.25 218 Harmful if inhaled. Causes respiratory tract irritation. Readily absorbed when inhaled. Material volatilizes at room temperature. Hemolytic anemia (destruction of red blood cells) is the primary health concern for humans exposed to naphthalene for either short or long periods of time. Other effects may include nausea,

profuse perspiration, vomiting, kidney damage and liver damage. Optic neuritis (inflammation of the optic nerve) has been observed. Cataracts have also occurred 3-nitroaniline 138.14 0.901 114 306 Blue lips, fingernails and skin. Headache. Dizziness. Nausea. Confusion. Convulsions. Labored breathing. Unconsciousness. May cause respiratory tract irritation. Chronic: May cause liver and kidney damage. Isopropanol 60.1 0.79 -89 82.5 Highly flammable liquid and vapor. Causes serious eye irritation. Repeated high exposure can cause headache, dizziness, confusion, loss of coordination, unconsciousness and even death. DANGEROUS FIRE HAZARD Sodium Hydroxide 39.997 1.515 318 1388 Hazard statements: May be corrosive to metals. Causes severe skin and lung burns and eye damage. Contact with water causes violent frothing and spattering. Reacts with metals to produce highly flammable hydrogen Sodium Bicarbonate 84.007 1.1 300 851 Coughing and sneezing if a high concentration of dust has been inhaled. Not too dangerous or listed as a hazard by OSHA. Hexane 86.18 0.66 −96 to −94 ° 8.5 to 69.1 ° Highly flammable liquid and vapor. May cause drowsiness or dizziness. Suspected of damaging fertility or the unborn. - May be fatal if swallowed and enters airways. Observations: (Include pictures of TLC plate)

In the first lane was the naphthalene indicating an impurity from the two spots in that lane. In the next lane is the Benzoic Acid, with an Rf value of about 0.55. Then in the third lane is the 3-nitroaniline which does not show that it traveled very far with an Rf value of about 0.22. Lastly, the mixture of all of it shows indicates the 3 components with the three spots which is what we expected. The last lane also indicates that possibility of 3-nitroaniline is high because of the position of that spot that did not travel far to the solvent line. Tabulated data (10 points): (construct a table including name of compound, distance spot traveled, distance solvent traveled, calculated Rf values for each spot visualized, amount (g) material recovered, and percent recovered for each material) Compound Distance Solvent Traveled (cm) Distance Spot Traveled (cm) Rf Values Amount (g) recovered Percent recovered Naphthalene 4.5 cm 4.2 1 0.95 0.22 0.039 65% Benzoic Acid 4.5 cm 2.5 0.55 0.034 56.7% 3-nitroaniline 4.5 cm 1.1 0.24 0.035 58.3% Mix of all above 4.5 cm 1 2.6 4.3 0.22 0.62 0.96 N/A N/A

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Answer the questions below (25 points): 1. Which compound was primarily recovered in each test tube (A, B, and C)? How much of each material did you recover? Where is the rest of the material? How could you recover more material from each tube? The 3 compounds recovered in each tube were Naphthalene (neutral), 3-nitroaniline (Base), and Benzoic Acid (Acid), respective to test tube A, B, and C. We recovered 0.039 grams of the Naphthalene from test tube A, 0.035 grams of 3-Nitroaniline from test tube B, and 0.034 grams of Benzoic Acid from test tube C. Each compound originally contained 0.06 grams and as expected we could not yield 100% of it. Besides human error, there was just some compound lost in the experiment that we were not able to recover. We saw much of the compounds in the test tubes as residue as well as not enough of the compound was extracted from the mixture since we only had time to do one extraction and not repeat them. To recover more material from each tube you could add the water to rinse off the residue in test tube B. And in the other tubes it would increase the yield if you repeated the extraction steps. The method of extraction we used is not the most precise and it could have very well left some of that compound behind. 2. Explain any anomalies that you observed in your TLC plate (e.g., streaking or large spots). The TLC plate showed somewhat consistent sized spots and only some abnormalities. For naphthalene there must have been another substance or impurity which caused two spots to appear. There was also streaking that occurred in the last lane with the mixture compound due to possible spotting error on our end. 3. Discuss the purity of each compound isolated and use your data to support your claims. Based on the evidence of the TLC plate we were not successful in extracting the pure Naphthalene. The two circles indicate that there was something left in the solution. This could also contribute to the percent yielded which was in fact higher than the other two compounds. The Benzoic Acid was somewhat successful as there was only one spot on the TLC plate and no streaking or additional spots. However, the percent yielded was low compared to the theoretical 100% we should have gotten. The actual compound isolated does show that it was pure on that TLC plate. The 3-Nitroaniline isolated extracted also seemed to show that it was pure. There was only one spot for it on the TLC plate indicating that that was the only compound present for that spotting. This extraction was also not completely successful in terms of percentage yielded 4. How would you change the procedure to increase the yield of any of the three materials? In the procedure, the amounts scraped out of the test tubes left behind a lot of compounds. If there was a way to efficiently transfer the material without it getting stuck to the sides and throughout the test tube, the outcome of the product would be much greater, like a lab spatula. Also, I would allow the students to do more than one extraction for each one. I would also add in the lab manual that adding water to test tube B would not change the compound and would only rinse the residue off into the vacuum filtration system. And it is

possible that using a laboratory Platform Shaker like a vertex with the diethyl ether in the very beginning would allow mix the solids faster without as large of an addition of diethyl ether. 5. How would you change the procedure to increase the purity of any of the three materials? Extracting each compound several times would increase the purity of the three materials. Being able to see what other compound was in the TLC plate lane for Naphthalene would be a way for us to know where we went wrong in our experiment, and we could prevent it from happening again. Also, discarding the one milliliter of liquid containing the diethyl ether and aqueous layer during extractions would decrease the risk of leaving one material in the test tube that was made for another material. This in turn however would decrease the yield precipitated overall.