The purpose of this lab is to be able to calculate the molar ratio of water to salt in a hydrate.
In this experiment, I took and empty crucible then weight it. After, I put 5 g of copper sulfate and recorded the mass. I then heated the crucible with a Bunsen burner, and rerecorded the mass and color change if any. I then repeated the same steps, this time using chloride hydrate.
Experiment #1 Experiment #2
Mass of empty crucible Mass of empty crucible
crucible + 5g copper sulfate (g) 93.000g crucible + 5g magnesium chloride hydrate (g) 93.000g
mass after heat is applied (g) 91.196g mass after heat is applied (g) 90.342g
Empirical Formula of a Hydrate
Copper sulfate Mass: 93.000-88.000g= 5.000g 93.000g-91.196g=1.804 grams of water
The molar ratio of salt in the sample is 5:1
93.000-90.342=2.658 grams of water
2.342g/95.211g/ moles=0.025 moles molar ratio of water and salt 6:1
Results: The percent of water the sample hydrate that was given was determined by heating the sample of hydrate to remove the water, and from the data and results collected an empirical formula of the hydrate was able to be determined.
After heating the copper, it changed from a blue color to a grey. The chloride hydrate had no change in color.
Exp 1Exp 2
Mass of water in the hydrate sample 1.804 grams 2.658 grams
Moles of water in the hydrate sample 0.100 moles 0.148 moles
Mass of anhydrous salt in the sample 3.196 grams 2.342 grams
Moles of anhydrous salt in the sample 0.020 moles 0.025 moles
Molar ration of water to anhydrous salt in the sample 5:1 6:1
Conclusion: The purpose of this lab is to be able to calculate the molar ratio of water to salt in a hydrate. During the lab I learned that when hydrates are heated, they decompose into water and a crystal structure that differs from the original salt. Within this experiment we empirically determined the ratio of water to salt in the hydrates copper sulfate hydrate and magnesium chloride hydrate.