Experiment 5 The Percent of Water in Hydrated Barium Chloride

Experiment 5 The Percent of Water in Hydrated Barium Chloride 

The water that is trapped within the crystal structure of some ionic compounds (the water of hydration) can be removed easily by heating. The amount of the water present in a given sample can be determined by weighing the sample before and after this heating. The weight loss that occurs is the weight of the water in the sample. The percent of water in the hydrate is calculated as it is in a loss-on-drying experiment. 

In this experiment, the percent of water in BaCl2-2H20 will be determined. You will do the experiment in duplicate (run two determinations at the same time) and report two answers. 

One problem encountered in this procedure is that a small amount of the BaCl2-2H20 may be evaporated along with the water when the sample is heated. This would obviously cause an error because the weight loss would include more than just the water. To ensure that this does not happen, do not heat the sample directly with the flame of a burner, but rather, use the radiant heat obtained from a flame-heated ceramic-centered wire gauze. 

The theoretical percent of water in any hydrate can be calculated from atomic and formula weights. It is recommended that you perform this calculation and compare your results with this theoretically correct value. Try to account for any deviation. Since your sample of BaCl2-2H20 is as received, it may have additional water adsorbed due to room humidity. 

---