Formula of a Hydrate
Purpose: To determine the formula of a hydrate using chemical formulas, moles and molar mass.
Background Information: Hydrates is a salt that is bonded with water molecules. It is considered a inorganic salt because it is not carbon based. Salt is a term used to discribe a Ionic bonded substance with metal cation a non metal cation.
The water molecules can be removed from a hydrate by heating it.
Hypothesis: Not Applicable
Materials & Equipment:
Salt·nH2O (2-3g per group)
Hot plate Crucible tongs
Distilled water Rubber policeman
Crucible Bunsen burner
Filter paper 250ml beaker
Electronic balance Other equipment is available upon request
Procedure: In this lab we heated 3.2 grams of CuSO4•nH2O in a crucible over a Bunsen burner for a few minuets. We waited for the water to leave the substance by applying the heat. We could tell this process was happening by the change in color of the mixture from blue to whitish green. We then proceeded to weigh the substance again to determine how much water was in the substance.
Safety Issues & Other Suggestions:
-The hydrate is toxic by ingestion
-Always when dealing with flame be sure to keep objects like clothing and hair out of flames and to keep a diligent watch of whatever you are heating.
-The object you used to heat the Hydrate in can be very hot and a potential fire/burn hazard
Findings:
Mass of CuSO4•nH2O= 3.2g
Mass of CuSO4•nH2O after applying heat= 2.44g
Molar mass of CuSO4•nH2O 159.59g/mol
2.44g CuSO4•nH2O / 160g/mol CuSO4•nH2O= .0152
.76g CuSO4•nH2O / 18g/mol CuSO4•nH2O= .0422
.0152/.0152=1mol
.0422/.0152=2.776 molecules H2O
Our salt was found to have 3 molecules of water.
Possible Errors: Sense copper sulfate is a pentahydrate meaning it has 5 water molecules our data is wrong we should have 5 molecules of water not three. The main source of error was that we may not have heated the hydrate long enough to get off all of the water that was in the mixture. Also errors made while weighing such as not fulling zeroing our scale could also contribute to this error
This lab we were given copper sulfate and asked to figure out how many water molecules it had. I really liked this lab because we had to think a lot outside the box to figure out how to solve this lab.
