Coppin State College s1

Coppin State College Department of Natural Sciences

Chemistry 101.001 Dr. Alfred N. Amah

Dr. P. Krishnan

Experiment V-DETERMINATION OF WATER OF HYDRATION

NAME______ID#______Date______Sec.002

Last First

Data Sheet

Weight of empty (MT) crucible ______

Weight of empty crucible and sample, g ______

Weight of sample, g ______

Weight of crucible and sample:

after first heating ______

after second heating ______

after third heating ______

Weight of water lost ______

Percent of water in sample ______(determined from this experiment).

Formula of anhydrous salt ______

Number of moles of anhydrous salt ______

Number of moles of water ______

Number of moles of water in the formula of the hydrate ______

Formula of hydrate ______

Procedure:

Weigh out 2-3 g of the hydrated salt in a crucible using a triple-beam balance. Heat the hydrated salt as directed by your Instructor until a constant weight is obtained. Calculate the weight in grams of water lost from the hydrated salt. From this inforomation, determine the value of (x) in the formula of the hydrated salt. The salt used in this Experiment is CuSO4 .xH2O. [ Hint: use the methods outlined in the text for the calculation of Empirical Formula] (Cu = 63.546; S = 32.066; O = 16.00; H = 1.00, Ca = 40.078)

grams moles mole ratio formula

CuSO4:

H2O:

Questions to answer and turn in to the Instructor after the experiment:

1. Copper sulfate forms several hydrates: CuSO4.H2O, CuSO4.3H2O, and CuSO4.5H2O. A student determined that an unknown CuSO4 hydrate lost 25.3% of its weight upon heating. Which hydrate did the student have? Show your work.

2. A commonly used hydrate of CaSO4 is plaster of Paris, which contains 6.21% water. What is the formula for plaster of Paris? Show your work.

3. Gypsum, CaSO4.2H2O is another hydrate of CaSO4. How much water would 5.00 g of gypsum lose if the water of hydration were driven off? Show your work.