Lab 5 Formal Lab Report - Grade: 98% PDF

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determine amount of phosphorus present in the given fertilizer. I wanted to make sure that the amounts of nutrients: nitrogen, phosphorus, and potassium were the same as advertised. ...

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Phosphorus Content of Fertilizer Formal Lab Report Elizabeth Amanbayeva Experiment Summary In this experiment, I needed to determine amount of phosphorus present in the given fertilizer. I wanted to make sure that the amounts of nutrients: nitrogen, phosphorus, and potassium were the same as advertised. In order to test the amount of phosphorus in the fertilizer, I mixed the contents with other solvents to isolate the phosphorus of the fertilizer and determined whether or not the advertised amount of phosphorus was correct. In order to determine the amount of phosphorus in the given simple of fertilizer, there were a few steps I had to follow. First, I had to determine the amount of fertilizer I needed to give me 0.500 grams of phosphorus. To do this I had to use the gravimetric analysis calculations listed below. 0.500g P

100g P2O5 43.64g P

100g fertilizer 30.0g P2O5 = 3.819 -> 3.82 g of fertilizer

Second, I had to weigh a sample portion of the provided fertilizer within 0.2 grams of the amount that was calculated from step one. My third step, I transferred the fertilizer to a beaker, making sure to rinse any fertilizer hanging to the paper with small amounts of water from a wash bottle. In my fourth step, I added approximately 10mL of deionized water to the beaker for every 1 gram of fertilizer in the beaker making sure not to go over 80mL of water. I had to make sure that I stirred the fertilizer/water mixture for at least 5 minutes to ensure that as much fertilizer was dissolved as possible. If I was unable to get the fertilizer dissolved all the way, I would have used a vacuum filtration apparatus. I would have done this by placing a pierce of filter paper in the top of a Buchner funnel, wet it with deionizer water, start aspirator, and ran the fertilizer sample

over the filter paper. I would have used water from my wash bottle to rinse the beaker and transfer all my solid material from the beaker onto the filter paper. I would have made sure to rinse a tiny amount of water over the filter paper to make sure the last races of soluble material were rinsed from the filter. Next, I would have removed the top portion of the Buchner funnel and rinse drops of liquid sticking to the inside of the lower funnel into the filtration flask. Then I would have transferred the filtrate back into my beaker. I make sure to rinse the filtering flask two times with water and adding the rinse to my beaker. My fifth step, I added 30mL of 20.0% m/v Magnesium sulfate heptahydrate (MgSo4.7H2O) solution to my fertilizer solution and stirred with a plastic stirrer. For my next step I made sure that I rinsed my graduated cylinder with deionized water before I measured and added 70mL of 1.0 M ammonium hydroxide (NH4OH) solution to my beaker and I constantly stirred until precipitate had formed. I then covered the top of the beaker with foil to minimize the amount of ammonia vapor escaped into the room and left the beaker undisturbed for about 15 minutes. After my precipitation had gone for 15 minutes, I used a clean pierce of filter paper in the Buchner funnel top and filtered everything my contents from the beaker by decanting out as much of the clear supernatant as possible before letting the solid go onto the filter. I made to rinse my beaker with small amounts of water until every bit of solid was transferred into the Buchner funnel. After all the traces of water was pulled out of the top of Buchner funnel and after the solid was transferred, I rinsed the solid on the filter twice with 10mL portions of deionized water. After the last trace of the second water rinse was pulled out of the top of the Buchner funnel, I rinsed the solid once with 10mL of 70% v/v isopropyl alcohol. As with the water rinse, I poured the alcohol over my whole sample. After the last trace of the alcohol rinse was pulled out of the funnel, I removed the Buchner funnel top from the filtration apparatus and carefully scraped the solid material onto my pre-

weighed Petri dish using a plastic stirrer. I made sure that I scraped as much of the solid residue from the paper in the Buchner funnel as possible. After my sample had time to completely dry, I finished my calculation and shared my percentage of P2O5 for my fertilizer sample with everyone in my lab. I also recorded all findings on my data sheet and recorded my lab members findings so I could calculate if we are all getting around the same data. Once everything was done and figured, I made sure to clean everything up that was used and discard everything properly. Results After all the filtration, my fertilizer sample looked came out as small cream-colored chunks. Here are my results from my calculations. The brand of fertilizer used was Expert Gardner All-Purpose Fertilizer with and advertised 30% of phosphorus. The mass of fertilizer needed to provide 0.500 g of phosphorus was 3.82g 0.500g P

100g P2O5 43.64g P

100g fertilizer 30.0g P2O5 = 3.819 -> 3.82 g of fertilizer

Mass of fertilizer used was 3.728 grams. Mass of petri dish with MgNH4PO4.6H2O was 46.127 grams. Mass of empty petri dish was 42.285 grams. To find the mass of MgNH4PO4.6H20 recovered, I subtracted the difference of the petri with my sample from the empty petri dish. 46.127 g – 42.285 g = 3.842 grams. I than calculated the grams of P2O5 in the fertilizer with the calculation shown below.

3.842g MgNH4PO4.6H2O

12.62g P

100g P2O5

100g MgNH4PO4.6H2O

43.64g P

= 1.111g P2O5 The percentage of

P2O4 found in my sample was 30.0%. I found this percentage by dividing the grams of P2O5 in fertilizer by the mass of fertilizer and then timing by 100. The calculation used is shown below. 1.111g P2O5/ 3.728g x 100 = 29.86% rounded to 30.0%. I recorded my lab classmates in the chart below to verify that we all got about the same percentage of phosphorus and that the advertised amount of phosphorus in the fertilizer was correct. Student Number 1 2 3 4 5 6 7 8 9 Class average

% P2O5 in fertilizer sample 30.84 32.24 30.17 29.80 28.64 28.79 29.52 28.93 30.61 29.95

Conclusion In this experiment, I needed to determine the amount of phosphorus present in the given fertilizer. After my calculations and results, I have concluded the percentage I calculated is around the same percentage of phosphorus advertised in the fertilizer. The percentage of P2O4 found in my sample was 30.0%. I found this percentage by dividing the grams of P2O5 in fertilizer by the mass of fertilizer and then timing by 100. The calculation used is shown below. 1.111g P2O5/ 3.728g x 100 = 29.86% rounded to 30.0%. My lab classmates averaged around 29.95% phosphorus making this experiment a success and acceptable. Student Number 1 2

% P2O5 in fertilizer sample 30.84 32.24

3 4 5 6 7 8 9 Class average

30.17 29.80 28.64 28.79 29.52 28.93 30.61 29.95

References Oklahoma City Community College. “Experiment 5-Phosphoeus Content of Fertilizer.” CHEMISTRY 1131 Laboratory for Survey of General, Organic, and Biochemistry, 2020 Editions, pp 45-50....