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Hydrates Unit 6 Lesson 3.

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Presentation on theme: "Hydrates Unit 6 Lesson 3."— Presentation transcript:

1 Hydrates Unit 6 Lesson 3

2 Hydrates Ionic compound that has water incorporated into its crystal structure

3 Hydrates Written as MgSO4●7H2O
Read 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 H2O molecules you have If finding the molar mass, include the water!

4 Hydrate Practice Name the following Hydrates and find their molar masses CuSO4 • 5H2O ZnCl2 • 3H2O Mg(NO3)2• 4H2O

5 Determining the Formula of a Hydrate
Example: Find the formula of a hydrate that is 48.8% MgSO4 and 51.2% H2O Step 1 – assume exactly 100 grams 48.8 g MgSO4 and 51.2 g H2O Step 2 – calculate moles 48.8 g MgSO4 (1 mol/120.38g) = .405 Moles MgSO4 51.2 g H2O (1mol/18.02g) = 2.84 moles H2O Step 3 – calculate mole ratio by dividing by smallest number of moles .405/.405 = 1 mole MgSO4 2.84/.405 = 7.01 moles H2O So there are 7 moles of water per 1 mole of MgSO4 MgSO4●7H2O

6 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 CoCl2 and 2.50 g H2O moles CoCl2 and moles H2O 0.0712/ = 1 mole CoCl2 0.139/ = 1.95 moles H2O CoCl2 •2H2O

7 Example: Finding mass percent from a hydrate formula
Determine the mass percent of the anhydrous portion and the water in the hydrate Na3PO4 •10H2O Find the mass of the anhydrous portion: 3(22.99g) g + 4(16.00g) = g Find the mass of the ten attached waters: 10(18.016g) = g Find the mass of the entire hydrate: g g = g Mass percent of the anhydrous: (163.94g/344.06g)100 = % anhydrous Mass percent of the water: (180.16g/344.06g)100 = % water


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