Unit 6 Lesson 3 Hydrates Ionic compound that has water incorporated into its crystal structure 2 Hydrates Written as MgSO 4 7H 2 O Read as Magnesium Sulfate Heptahydrate Means for every one MgSO ID: 571090
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Slide1
Hydrates
Unit 6 Lesson 3Slide2
Hydrates
Ionic compound that has water incorporated into its crystal structure
2Slide3
Hydrates
Written as MgSO
4
●7H2ORead as “Magnesium Sulfate Heptahydrate
”Means for every one MgSO4 you have 7 water molecules.Notice the prefixes we learned for naming covalent compounds are used to tell how many H
2
O molecules you have
If finding the molar mass, include the water!Slide4
Hydrate Practice
Name the following Hydrates and find their molar masses
CuSO
4 • 5H2O
ZnCl2 • 3H2O
Mg(NO
3
)
2
• 4H2O
4Slide5
Determining the Formula of a Hydrate
Example: Find the formula of a hydrate that is 48.8% MgSO
4
and 51.2% H2OStep 1 – assume exactly 100 grams48.8 g MgSO
4 and 51.2 g H2OStep 2 – calculate moles
48.8 g MgSO
4
(1 mol/120.38g) = .405 Moles MgSO
4
51.2 g H2O (1mol/18.02g) = 2.84 moles H
2
O
Step 3 – calculate mole ratio by dividing by smallest number of moles.405/.405 = 1 mole MgSO42.84/.405 = 7.01 moles H2OSo there are 7 moles of water per 1 mole of MgSO4
MgSO
4
●7H
2
OSlide6
Example
A hydrated Cobalt (II) Chloride sample has a mass of 11.75g. After being heated (to remove all water) the mass is 9.25 g. What is the formula for the hydrate?
9.25 g CoCl
2 and 2.50 g H2O0.0712 moles CoCl
2 and 0.139 moles H2O0.0712/0.0712 = 1 mole CoCl
2
0.139/0.0712 = 1.95 moles H
2
O
CoCl2 •2H2OSlide7
Example: Finding mass percent from a hydrate formula
Determine the mass percent of the anhydrous portion and the water in the hydrate
Na
3PO4
•10H2O
Find the mass of the anhydrous portion: 3(22.99g) + 30.97g + 4(16.00g) = 163.94g
Find the mass of the ten attached waters: 10(18.016g) = 180.16g
Find the mass of the entire hydrate: 163.94g + 180.016g = 344.06g
Mass percent of the anhydrous: (163.94g/344.06g)100 = 47.649% anhydrous
Mass percent of the water: (180.16g/344.06g)100
= 52.351% water