Gravimetric Determination of Moisture in Fertilizer Samples

GRAVIMETRIC DETERMINATION OF MOISTURE IN FERTILIZER SAMPLES

Institute of Chemistry, University of the Philippines, Diliman, Quezon City 1101 Philippines

Department of Chemical Engineering, College of Engineering, University of the Philippines, Diliman, Quezon City 1101 Philippines

Results and Discussion Report

Gravimetric analysis describes a set of methods in analytical chemistry for the quantitative determination of an analyte. A simple example is the measurement of solids suspended in a water sample: A known volume of water is filtered, and the collected solids are weighed.[1][2]

Gravimetric methods of analysis are based on mass measurements made with an analytical balance, an instrument that yields highly accurate and precise data.[1]

There are two types of gravimetric methods of analysis. First is the precipitation gravimetry. In precipitation gravimetry, the analyte is separated from a solution of the sample as a precipitate and is converted to a compound of known composition that can be weighed. The second one is the volatilization gravimetry. In volatilization gravimetry, the analyte is separated from other constituents of a sample by conversion to a gas of known chemical composition. The weight of this gas then serves as a measure of the analyte concentration. [1]

In the experiment, the crucibles were first heated in the oven. Before getting the weights of the crucibles, they are first cooled in a desiccator. This process is repeated until two consecutive weights are within 0.0002-0.0003 grams range.

In the second part of the experiment, a grinded fertilizer sample is first measured in the crucibles on the analytical balance by weighing by difference. Then, they are heated in the oven. Before getting the weights of the crucibles with fertilizer samples, they are first cooled in a desiccator. This process is repeated until two consecutive weights are within 0.0002-0.0003 grams range.

Using the data acquired from the...