Phosphorus Content In Fertilizer

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Magdato, K. C. , Balbuena, J. S.
Institute of Chemistry, University of the Philippines, Diliman Quezon City
Date Performed: August 27, 29 and September 3, 2014
Date Submitted: September 10, 2014
The experiment aims to use gravimetric method of analysis in determining the moisture and phosphorus content in a fertilizer sample which is important in plant growth. The procedure included constant weighing of the crucible and sample. The addition of ammonia and magnesium sulfate heptahydrate caused the formation of the precipitate identified as magnesium ammonium phosphate hexahydrate(MgNH4PO46H2O). The weight of the precipitate was used to determine the mass of
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%Pasreceived is 5.8±0.008% and %Pdry 12.7±0.008 and %P2O5asreceived 6.63±0.008 and %P2O5dry 14.48±0.008. This shows that there are also other components present in the fertilizer sample that is

The agricultural value of fertilizer samples depend on their total phosphate and water content. Natural phosphates are found in small amounts in all better types of soil and their presence is very important for plant growth. Phosphate content was determined as a precipitate magnesium ammonium phosphate hexahydrate.[1]
Moisture determination is an important indicator of the fertilizer 's quality. Nutrient content is dependent on the amount of moisture it contains. It is necessary to grind the sample so that fineness desired for the experiment is achieved.
In this experiment, gravimetric method of analysis was used. Gravimetric analysis is a method that involves precipitating and weighing the mass to determine how much of a certain substance is present. Precipitation is the first step in this method which can be broken down into two major processes. The initial step in the crystallization is called nucleation, the formation of the nucleus. The other process is called particle growth, the stage
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During precipitation, NH4Cl cannot be used in place of NH3 because the Cl- can react with Mg2+ thus forming MgCl2. And this is not a desired product in the reaction.
Table 1. Data Obtained
Constant Weight of Crucible38.3666 ± 0.0002 gConstant Weight of Crucible with Sample41.2928 ± 0.0002 g% Moisture2.45 ± 0.008%%P(as received)5.8 ± 0.008%%P(dry)5.95 ± 0.008%%P2O5 (as received)6.63 ±0.008%% P2O5 (dry)6.80 ±0.008%Using the values obtained, the mass of water, phosphorus, and P2O5 were determined. Calculations can be found in the Appendices.
These valued were used to calculate the percentages needed to determine the water and phosphorus content which can be found in the Appendices as well. Table 1 shows the overall data obtained in the experiment.
Based from the calculations done the percent moisture was found to be 2.45 ± 0.008%. %P(as received)= 5.8 ± 0.008% and %P(dry) = 5.95 ± 0.008%. While, %P2O5 (as received)= 6.63 ±0.008% and % P2O5 (dry)= 6.80 ±0.008%. This shows that the fertilizer also has macronutrients other than water and phosphorus which can be useful for plant growth. This experiment is successful since the results obtained
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