Elyssa Edgeton
College Chemistry
Wentzel Hour 3
11/11/14
Discussion of Theory
Our lab groups heated the hydrate CuSO4 * xH2O in order to evaporate the water in the
compound, and measured the mass change that occurred. This lab allowed us to observe how
hydrates, crystalline structures containing water, can be turned into anhydrous compounds once
the water is removed. We also applied our knowledge of how to find chemical formulas with
mass percents in order to find the chemical makeup of our hydrate. We assumed that water was
the only component evaporating from the compound, and caused all of the mass change. We also
assumed that the anhydrous compound, CuSO4, was the only remaining component, and had not
changed from its original form.
Sources of Error
Our group calculated the ratio of moles of H2O to CuSO4 and found that there was about a 5:1
ratio between the compounds. We did have a 1.76% error, however, meaning there was slightly
more mass from water than the integer we expected. This is probably due to the fact that we did
not have enough time to fully heat and dry the compound until there was no mass change, and
nearly all of the water was gone. This would mean that our observed percent of water to CuSO4
was actually less than it should be. Our scale was also not accurate to the 4th decimal, which
would affect our results’ accuracy as well.