Question

Post-Laboratory Questions (Use the spaces provided for the answers and additional paper if necessary.) 1. Briefly explain whether the following procedural changes would have caused the calculated number of waters of hydration in a hydrate sample to be too high, too low, or unaffected. (a) A student washed the crucible, but failed to heat it to dryness prior to weighing it at the start of the experiment. (b) A student was anxious to finish the experiment and heated the crucible containing the sample with a very hot burner flame, causing a small amount of the solid compound to splatter out of the crucible. (c) The crucible and sample fell from the ceramic triangle during a third heating. The sample did not spill, but a small chip broke off the crucible and was lost. 2. (a) Write the chemical equation for the formation of strontium oxalate monohydrate from strontium oxalate (SrC2O4). was used as a desiccant. Calculate the mass of the completely (b) A 0.500-g sample of SrC2O4 hydrated salt. (c) Suggest a method for regenerating the desiccant form of SrC,O, once the salt has been completely hydrated. Briefly explain. 3. Upon being heated, calcium oxalate monohydrate, CaC O4 H2O, undergoes a series of temperature- related changes as shown in Equations 6-8 oterodel- 2001 CaC2O4 H2O(s) 100-126 "C CaC2O4(s) +H2O(g) (Eq.6) 400-600 C CaCOs (s)+CO(g) CAC2O4(s) (Eq. 7) >600 C CaCO3(s) CaO(s) +CO2(g) (Eq. 8) A student paid little attention to the size of his burner flame while heating a 0.979-g sample of CaC O4 H2O. The final mass of the cooled solid was 0.670 g. (a) Was the reaction product anhydrous calcium oxalate? Briefly explain. (b) Assuming that the final product was pure, what was the final product? Briefly explain.

Answer 1

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