Gravimetric Analysis of Phosphorus in Plant Food

The purpose of our experiment was to gravimetrically determine the amount of phosphorus in different types of plant food and to find if the amount of phosphorus in the plant food had any effect on the price. We choose three types of plant food, one with a very low percent of phosphorus, one with a medium percent, and one with a very high percent. The plant food that had the lowest percent of phosphorus, 10%, was the cheapest. Plant food with a medium amount 30%, was second cheapest and the most expensive plant food had the highest percent, 60%. To find out what percent there really was in each type we designed and ran an experiment. We diluted the plant food in water and added MgSO4 and NH3NH4OH to make a precipitate called struvite. The chemical formula for Stuvite is MgNH4PO4 which contains phosphorus. We used vacuum filtration to filter the struvite out and then it was weighed. Our results showed that the percent of phosphorus shown on the box was higher then the actually amount of phosphorus.

Research Done By:

Elizabeth Newby
Warren Mott

Adam Hull