Hydrate Composition

Hydrate composition say what? Yes it is true, you can find out what percentage of a certain Hydrate is water. How do you do this miraculous deed? First you mass EVERYTHING. Mass the evap dish, and evap dish with compound hydrate. Then simply heat the evap dish with the substance on a ring stand over a bunsen burner. You then shall wait until the evap dish is cool, then mass that as well. Your mass should be lower than the first mass because you are evaporating water from you substance! To make sure you evaporated all the water out. Heat the evap dish again for 3-5 minutes! Then what do you do? MASS AGAIN. Your two masses after heating should only vary .02 if it differs any more than that you will have the pleasure to heat and mass again. Thankfully mine only differed .01 grams. Once you have all your data, you can put the mass of the water (which you can calculate by finding the mass of the hydrate which in my case was 2.08 g and the subtracting that from the second mass after the heating, which was 79.41 g) which is 1.32 g and divide this by the mass of the hydrate, 2.08 g. You should get .365 then multiply this by 100 and you have your answer 36%! Now does this mean the results are completely reliable? No! The stirring rod we used had some substance on it when taken out which could have effected the mass of the substances. If you used 6.0 g of hydrate you would still lose 36% due to our calculations which would approximate to about 2.16 g of water loss during the heating. The results could change if the hydrates spatted out because that effects the overall mass which would mess up the calculations. For example if approximately .05 grams spatted out, this means not all the hydrate may have evaporated which would largely affect the overall data collected.



mass wtr/mass hydrate X 100 = percent comp of hydrate

90.00 g H2O/249.60 g CuSO4 = 36.05% H2O

CuSO4 * 5H2O        Total mass of hydrate is 249.6 g because Copper is 63.50 g, Sulfur is 32.07g, O4 is 64.00g, H2O is 18.00 and you have 5, which means there’s 90.00 g H2O.

Percent Error:


actual-theoretical/theoretical     0 .76-0.75/0.75 = 0.01 Percent error

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