Question

Show the calculation for determining the mass % of P2O5 in a fertilizer sample (starting from the MgNH4PO4.6H2O product mass)

2. GRAVIMETRIC DETERMINATION OF PHOSPHORUS IN PLANT FERTILIZER 2.1 INTRODUCTION Gravimetric analysis is a method of quantifying an analyte through the determination.af. the mass (i.e. weight) of the analyte. In the following experiment, you will quantify the amount of phosphorus present in plant fertilizers by isolating the phosphorus content and reacting it to form a solid precipitate. This precipitate will be measured weigh-by-difference technique and the weight of the precipitate can be used to determine the initial amount of phosphorus in the fertilizer (by looking at the chemical reactions required to form the precipitate). using the Plant nutrients inorder for plants to grow healthy,they require these basilc chemical elements (isted below in order of importance): Carbon (C), hydrogen (H), and oxygen (O): readily obtained from water and carbon dioxide Nitrogen (N), phosphorus (P), and potassium (K): called primary macronutrients Sulfur (S), calcium (Ca), magnesium (Mg): called secondary macronutrients -Boron (B), chlorine (CI), manganese (Mn), iron (Fe), zinc (2n), copper (Cu). molybdenum (Mo): referred to as micronutrients Soil generally provides the macro and micronutrients, however, the primary macronutrients (N, P, and K) are so crucial for plant growth and survival, that plants can deplete soil of these nutrients during early stages of growth. Plant fertilizers are generally added to soils to provide an additional supply of the primary macronutrients (and in some cases to add micronutrients). Plant fertilizer Plant fertilizers represent the amount of primary macronutrients with a 3 number label, often referred to as the N-P-K value. The N-P-K value is the mass percent of Nitrogen, the mass percent of phosphorus (in the form P:O) and the mass percent of potassium (in the form K,0') in the fertilizer. In Figure 2-1:A fertilizer with the NPK figure 2-1, a bottle of value of 12-55-6 which indicates that the Green light SuperBloom™ fertilizer loom is shown and we see the the fertilizer is composed of 12% N, 55% P,01, and 6% K,0. Adapted from Solomon, S, Lee A, Bates D. J. Chem. Ed. 70, 1993, 410-412 The reason that phosphorus is expressed as P,0, and potassium is expressed as K,O is because in earlier quality control studies of fertillzer, scientists would do gravimetric analyses after igniting samples and then measure the oxdized components of the fertilizer, P:0s and K,o.