Calcium chloride, a deliquescent salt, is used as a desiccant in laboratory desi
ID: 487284 • Letter: C
Question
Calcium chloride, a deliquescent salt, is used as a desiccant in laboratory desiccators to maintain a dry environment Explain. Experimental Procedure. Part A 1 What is the purpose of firing the crucible? A 1.803-g sample of gypsum, a hydrated silt of calcium sulfate. CaSO_4, is heated at a temperature greater than 170 degree C in a crucible until a constant mass is reached. The miss of the anhydrous CaSO_4, salt is 1.426 g. Calculate the percent by mass of water in the hydrated calcium sulfate salt. The gravimetric analysis of this experiment is meant to be quantitative; therefore, all precautions should be made to minimize errors in the analysis. The crucible and ltd are handled exclusively with crucible tongs in the experiment. How does this technique maintain the integrity of the analysis? Mass measurements of the crucible, lid. and sample are performed only at room temperature. Why is this technique necessary for a gravimetric analysis?Explanation / Answer
Q1.
CaCl2 will "absorb" water/moisture from air, in order to form CaCl2*xH2O crystals, that is, H2O will be removed from the ambient
Q2.
Firing cruicible ensures no other species presence
Q3.
m = 1.803 g of CaSO4*xH2O
mass of CaSO4 = 1.426
mass of hydrate = 1.803-1.426 = 0.377 g of water
% water = 0.377 / (1.803 ) * 100% = 20.909%
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