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Gravi Protocol - (Mg(NH 4)PO 4)6H 2 O and filter off...

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Group Team Car Ramrod Bombers Members: Jonathan Brate, Anna Cumtell, Carter Stitt, Ed Lynch Gravimetric Analysis Protocol Constructing the Calibration Curve 1. Weigh out 1.309 g of Fertilizer. 2. When determining how much fertilizer sample will be needed in step1, assume the fertilizer contains approximately 13% P by weight. 3. Dissolve the sample in about 10 mL of deionized water in a 50 mL beaker. 4. When formulating the protocol for the fertilizer analysis, you should also filter the dissolved sample by gravity to remove any insoluble impurities. 5. Add 10 mL of the 0.4 M MgSO 4 solution. 6. Slowly add 1 mL of the 6M NH 3 , using a disposable pipet, while stirring. 7. After adding all of the NH 3 , touch the stirring rod to a piece of red litmus paper. 8. Repeat, adding 1 mL of NH 3 at a time until the litmus paper turns blue when in contact with the solution, then add 0.5 mL more of NH 3 . 9. Let the solution precipitate for about 15 minutes to complete the precipitation of
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Unformatted text preview: (Mg(NH 4 )PO 4 )6H 2 O, and filter off precipitation using suction filtration. 10. Wash the precipitate with two 5-mL portions of isopropyl alcohol. 11. Suck air through filter for about 20 minutes to help dry the precipitate and then carefully scrape it onto a pre-weighed watch glass, making sure to get all of the precipitate. 12. Let the precipitate dry in air for half an hour and weigh the watch glass with precipitate. If the precipitate is not dry, don’t weigh it. 13. While you are waiting for the product to dry, perform a second trial by the previous steps. 14. Measure the mass of the product and use this to determine the % P 2 O 5 in the sample. 15. Show how you will use the mass of (Mg(NH 4 )PO 4 )6H 2 O formed to calculate the percent P 2 O 5 in the original sample. 16. Ideally, you should have at least three significant figures in your final percent of P 2 O 5 ....
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