Experiment: Percent Water in a Hydrated Salt

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Experiment 5: Percent Water in a Hydrated Salt

Chemistry 1300
Instructor:
2/8/12

Abstract:

The purpose of this experiment was to determine the percent by mass in a hydrated salt, as well as to learn to handle laboratory apparatus without touching it. The hydrated salt, calcium carbonate, was heated with high temperature to release water molecules. Gravimetric analysis was used in this experiment to determine the percent by mass of water in a hydrated salt. The hypothesis of this experiment was accepted on the basis that the percent by mass of volatile water in the hydrated salt would be fewer than 30%. The percent by mass was determined by the mass of water loss devised by the mass of hydrated salt multiplied by total capacity (100%). The purpose of this experiment was to determine the percent by mass in a hydrated salt, as well as learn to handle laboratory apparatus without touching it. Most substances have water as a part of its composition, either absorbed or bonded to the substance. Many salts in nature, the grocery store, or from chemical suppliers are chemically hydrated with water molecules, referred to as the waters of crystallization. Anhydrous salts are sometimes created when heat is applied to the salt removing the water molecules. Some salts have strongly bonded water molecules that will not cause the formation of anhydrous salts, regardless the intensity of the heat. 1

Tongs were needed throughout the entire experiment to maintain a safe environment and keep fingers from being scorched by the hot crucibles. The tongs were also a major factor in conducting the experiment. The oil from the fingers can contaminate the surface of the crucible and lid. The oil on the crucible can add mass and jeopardize the integrity of the experiment.

The gravimetric analysis method relied mainly on the mass measurements recorded to determine the percent by mass in hydrated salt. The mass of the hydrated salt is measured, then the sample is heated. The...
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