1. Mrs. Coyle Honors Chemistry
Hydrates
Mrs. Coyle Honors Chemistry

2. Hydrate:
A crystalline compound in which the ions are attached to one or more water molecules.

3. Example:
CuSO4•5H2O
copper(II) sulfate pentahydrate

4. Prefixes for naming Hydrates
mono- 1
di- 2
tri- 3
tetra- 4
penta- 5
hexa- 6
hepta- 7
octa- 8
nona- 9
deca- 10

5. Analyzing Hydrates Simulation click on the link below:

6. Problem 1:
A sample of 0.235g of hydrated salt of cupric chloride is heated to 100oC. The mass of the sample remaining after heating is 0.185g.
a) What percent by mass of the hydrate is
water?
b) How many moles of water are there for each mole of cupric chloride?

7. Problem 1 : Solution Mass of water in the sample =
=0.235g g =0.050g
% by mass water =
=(0.050g/0.235g)x 100% =21.% by mass

8. Problem 1: Solution Cont’d
b) Molar Mass of CuCl2 = Cu g
+Cl 2(35.453g) g
# mol CuCl2= g x 1mol g
=1.38x10 -3mol CuCl2

9. Problem 1: Solution Cont’d
Molar Mass H2O = H 2(1.008g)
+O g g
# mol water= 0.050g x 1 mol =
18.010g
=2.78 x10-3 mol water

10. Problem 1: Solution Cont’d
# mol water = 2.78 x10-3 mol water =
#mol cupric chloride 1.38x10 -3mol CuCl2
= ≈ 2
So the formula of the hydrate is:
CuCl2 ∙ 2 H2O