LAB_03_PercentWaterDeterminationAlumDGCF09

# LAB_03_PercentWaterDeterminationAlumDGCF09 - Pre-lab...

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1 9/09 DGC Pre-lab Assignment Percent Water in Alum 1. What are solid chemical compounds that contain a stoichiometric quantity of water known as? 2. Describe how you know experimentally when you have obtained c on st an t ma ss . 3. Determine the theoretical % water in Alum (KAl(SO 4 ) 2 12H 2 O). Cl e arly s how all your c al c ulation s in your lab book! 4. Use the following data to calculate the % water in the sample of Alum. Crucible 1 Crucible 2 Constant mass of crucible 22.038 g 23.176 g Constant mass of crucible and Alum sample b e for e heating 23.108 g 24.210 g Constant mass of crucible and Alum sample aft e r heating 22.604 g 23.749 g a) From the above results, calculate the percent water for each sample. b) Calculate the average percent water present. c) Calculate the percent error for the average compared to the theoretical value you obtained in this pre-lab exercise. Cl e arly s how all your c al c ulation s in your lab book! Remember to report your final answers with the proper number of significant figures. .

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2 9/09 DGC DETERMINATION OF PERCENT WATER IN ALUM SALT Introdu c tion: The Alum salt is one of a number of solid chemicals that are classified as hydra t e s . A contains water chemically bound in the solid state so that it is present in the compound in stoichiometric amounts. (Familiar examples of hydrates are gypsum, CaSO 4 2H 2 O; plaster of paris and CaSO 4 ½ H 2 O.) The water of hydration of many hydrates can be removed as a gas by heating the hydrate to a temperature above 100ºC for a period of time. Equation 1 gives the reaction involved when barium chloride dihydrate,
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## LAB_03_PercentWaterDeterminationAlumDGCF09 - Pre-lab...

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