Lab #9: Composition of a Copper Sulfate Hydrate Lab

Hydrate Photo 

Before




















The hydrate was a deep blue color and very crystalline. Had a very dark and bold color.

After                                                                                                                                                        
















The anhydrate was a powdery light gray color, at odds with its original deep blue. There were still some patches of light blue in the evaporating dish as well, but this was due to the larger chunks of hydrate that we could not crush up.

Calculations #1-4

Problem #5: Data and Formula

To find the coefficient of water, we first found the mass of the evaporated water and the anhydrate remaining in the evaporation dish; this was done by manipulating the data shown above. Next we converted the masses for each of these values into moles. Finally, we divided each mole calculation by the smaller mole value and thus got the formula for copper sulfate hydrate. The coefficient for water was found to be about 4.8; however, we just decided to round it up to five.
       
                                                                      CuSO4 *5 H2O   

Percent Error and Why
  Our percent error, we found , was about 2.22% because our value for the percent water was lower than the expected value--35.2% instead of 36%. We believe that this is due to the fact that our hydrate did not become an anhydrate entirely; it had not turned the same shade of pearl gray throughout, for it still had patches of light blue. This, we believe, is due to the fact that the water had not completely evaporated; however, we were running out of time and just decided to take the data for what it was. This would be a cause of error in our calculations. As a result, I believe that this would make our predicted coefficient for  water lower than it actually is because our calculated percentage of water is lower than the expected value as well.