Gravimetric Determination of Moisture and Phosphorus Content in Fertilizer Samples

GGravimetric Determination of Moisture and Phosphorus in Fertilizer Samples

Sager, Angelyn J.

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

August 15, 2014

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September 10, 2014

I.ANSWERS TO QUESTIONS

1. Why is constant weighing important?

Sometimes, exposure of the objects to air will increase their weight as they absorb moisture and humidity conditions and temperature vary from time to time causing its composition vary and same with the difference of the measurements. That is why constant weighing is practicing inside the laboratory.

By this process, the true weight of the object can be determined and these values can be duplicated in experiments that use the same object, and thus minimizing the error due to the presence of moisture in the sample.

2. Why is moisture determination important in fertilizer samples?

The moisture content of fertilizers is an important indicator of its quality. The nutrient content or grade of the fertilizer is dependent on the amount of moisture that it contains. Moreover, there is a legal limitation to the minimum or maximum amount of moisture that a fertilizer can carry. If the moisture content exceeds or falls short of the recommended level, the quality deteriorates which may lead to unwanted caking and dust formation.

3. What are the other methods used in determining moisture content?

Other methods for drying are available such as infrared drying, halogen drying and microwave drying, but the drying oven was used because it is the most accessible, and multiple samples can be determined at once.

4. What are the advantages of weighing by difference over direct weighing?

This method is statistically preferred because of smaller error propagation during weighing. Deviations from the true weight due to spilling the sample inside the balance are prevented because all transfers between the vial and the crucible are performed outside...