30AL Soil Project

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Chemistry

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Dec 6, 2023

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CHEM 30AL : General Chemistry Laboratory II Soil Project Lab Report Unknown #12 Arnav Jhawar, Maggie Clark, Jessica Gonzalez TA: David Deluca Section: 1E

CHEM 30AL Soil Project Lab Report Group Responsibilities Arnav Jhawar : - Performed extraction, identification, and analysis of the inorganic molecules within the solution created from the unknown. - Conducted various tests, including Beer’s law, metal ion tests, and assisted in the analysis of the organic material on day 3 of the lab. - Assisted and contributed to the creation of the presentation slides, presented and contributed to the report. Maggie Clark : - In charge of the extraction, identification, and analysis of the organic molecules within the solution, created from the unknown. - Assisted in tests needed for organic analysis (TLC, mass spectroscopy, acid-base separation, UV spectrum, and melting point analysis). - Assisted and contributed to the creation of the presentation slides, presented and contributed to the report. Jessica Gonzalez : - In charge of the extraction, identification, and analysis of the organic molecules within the solution, created from the unknown. - Assisted in tests needed for organic analysis (TLC, mass spectroscopy, acid-base separation, UV spectrum, and melting point analysis). - Assisted and contributed to the creation of the presentation slides, presented and contributed to the report.

CHEM 30AL Soil Project Lab Report Abstract This project aimed to examine and understand the different substances present in a soil sample of unknown origin, labeled as sample 12. Through a series of experiments, we successfully identified and measured the amounts of both organic and inorganic compounds within the sample. The organic compounds found were naphthalene, a neutral substance, and m-nitroaniline, a basic substance. On the other hand, the inorganic compounds discovered were nickel (II) chloride (NiCl 2 ) and cobalt (II) sulfate (CoSO 4 ). To separate the organic and inorganic components, we utilized vacuum filtration after dissolving the sample in a mixture of hexane and ethyl acetate because one is polar and the other is non polar. We also employed an acid-base extraction to further separate the organic neutral and organic basic compounds from each other. For identification purposes, we utilized UV-vis, IR, and mass spectroscopy, and the compounds were purified through multiple liquid-liquid extractions. To assess the compound’s purity, we conducted TLC and melting point analyses. Similarly, for the inorganic compounds, we used UV-vis spectroscopy and specific tests to determine their presence. To obtain quantitative data, we performed colorimetry, a method that measures the intensity of color, based on which we analyzed Beer's Law. Calculations showed that the percentages by mass of the compounds in the sample were as follows: 1.4% naphthalene, 0.7% m-nitroaniline, 7.14% nickel chloride, and 4.48% cobalt sulfate.

CHEM 30AL Soil Project Lab Report Design and Discussion of the experimental procedure Separating the Organic and Inorganic: 1. We weighed approximately 25 g of the unknown mixture and recorded the appearance and exact weight. 2. Dissolved the unknown mixture in a nonpolar organic solvent- which was a mixture of hexane and ethyl acetate. 3. We Gently stirred the solution with a glass stirring rod. 4. Poured the solution into a vacuum filtration setup. 5. Collected the filtrate and stored it in a separately labeled beaker “organic compound.” Green/yellow color. 6. Dissolved the residue in water and stored it in a separate beaker labeled “inorganic compound.” Red/brown color. Organic: 1. We ran an initial TLC test using a mixture of hexane and ethyl acetate at the bottom of the jar and found that the organic layer was most likely Naphthalene (neutral) and m- nitroaniline (basic). 2. Placed solution into a separatory funnel to perform liquid-liquid extraction with HCl to protonate the basic part of the organic layer because it was now neutral. 3. This made the m- nitroaniline move into the aqueous layer and make

CHEM 30AL Soil Project Lab Report the organic layer neutral. For only the 1st extraction we collected an aqueous layer in the beaker. 4. Repeated 5 times so the neutral organic layer was pure. For the other 4 extractions, aqueous was waste. 5. Added drying agent to neutral organic and air dried to get white precipitate. This is Naphthalene. 6. Added a base to aqueous to deprotonate the m- nitroaniline, add until ph>7, some precipitate forms, this was the m- nitroaniline. 7. Conducted a liquid-liquid extraction with the aqueous solution from #6 with ethyl acetate to dissolve the precipitate. Repeated three times. 8. took an ethyl acetate layer, added a drying agent, air dried, and got a yellow precipitate. This was m- nitroaniline. 9. Ran TLC, melting point, UV vis, IR spec, and mass spec on both the basic and neutral. Inorganic: DAY 1 1. The inorganic solution was not pure, so an initial liquid-liquid extraction with ethyl acetate was necessary to wash the solution. 3 washes were done to purify. There was still some organic in this aqueous solution that needed to be washed out. 2. Solution was ready to run metal tests.

CHEM 30AL Soil Project Lab Report 3. Culture Tube #1: A small amount of the inorganic solution was added. Ammonium hydroxide was added and nothing happened. Dimethyloxirane was added and the solution turned a bloody red. This indicates that we have Nickel. There was only one Nickel option that could be in the unknown, so we could conclude that we had NiCl 2 4. Culture Tube #2: A small amount of the inorganic solution was added. Potassium Nitrate added and nothing happens. The culture tube was placed into a heating bath and yellow precipitate formed. This indicates that we have Cobalt. We had to determine if we had CoCl 2 or CoSO 4 5. Culture Tube #3: A small amount of the inorganic solution was added. BaNO 3 was added and white precipitate formed. This indicates that there is SO 4 -2 6. Culture Tube #4: A small amount of the inorganic solution was added. AgNO 3 added and white precipitate forms. This indicates that there is SO 4 -2 and Cl - are present. By inductive reasoning, we determine that we must have CoSO 4 Inorganic: DAY 2 1. Added 4.017 g of NiCl 2 to 50 mL of water. This was the stock solution. 2. Made 3 standard solutions. Solution #1: 15 mL of stock in 25 mL volumetric ﬂask, diluted to the mark with water. Solution #2: 20 mL of

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