one way to analyze the amount of phosphorus in a rock is to precipitate
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Step 1: Prepare the rock sample by crushing it into a fine powder to increase the surface area for the chemical reactions. Show more…
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Relate gravimetric analysis to the phosphorus content in plant food. Include the form in which phosphorus exists in plant food and the ion you used to precipitate the phosphorus. (5 points)
Adi S.
Phosphorus may be determined analytically by precipitating it as MgNH4PO4 followed by ignition to Mg2P2O7. What mass of Mg2P2O7 will be obtained from a 9.346 g sample of phosphate rock which contains 71.24% Ca3(PO4)2?
Experiment for Gravimetric Analysis: The Determination of Phosphorus in Plant Food Gravimetric analysis is a quantitative (i.e., how much?) method of classical analysis. The element to be determined is isolated in a solid compound of known identity. The mass of the element that was present in the original sample can be calculated from the mass of this compound. Plant foods contain three essential nutrients that are often in short supply in soils. These are soluble compounds of nitrogen, phosphorus, and potassium. A typical plant food will have a set of numbers such as 15-30-15. This means that the plant food is guaranteed to contain at least 15% nitrogen, 30% phosphorus, and 15% potassium (expressed as K2O). The remaining of the product consists of anions and cations to balance the charge in the chemical compound. This experiment is a quality control analysis for the determination of phosphorus using gravimetric analysis. Phosphorus will be determined by precipitation of magnesium ammonium phosphate hexahydrate according to the reaction: HPO4^-2 (aq) + NH4^+ (aq) + Mg^2+ (aq) + OH^- (aq) → MgNH4PO4·6H2O(s) The % P2O5 in the initial sample can be calculated from the mass of the precipitate.
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