1. Hydrates (11.5) Hydrate- compound with a specific amount of water molecules bound to it

2. Hydrates are often used as drying agents or desiccators because they can absorb moisture Silica gel- used in electronic equipment packaging, cat litter

3. Chemicals that do not contain water in their structures are called anhydrous (without water) Hydrates are easy to spot because their formulas show the water molecules Anhydrous cobalt (ii) chlorideCobalt (II) chloride hexahydrate CoCl 2 CoCl 2 x 6H 2 O

4. To determine hydrate formula 1.Determine moles of water and of anhydrous compound 2.Find x = moles of water moles of anhydrous compound 3.Plug in x Formula for compound X H 2 O

5. A mass of 2.50 g blue hydrated copper sulfate (CuSO4 x XH 2 O) is place in a crucible and heated. After heating, 1.59 g of copper sulfate remains. What is the formula for the hydrate? 2.50 = CuSO 4 + H 2 OCuSO 4 = 1.59 g 2.50 = 1.59 + H 2 OH 2 O = 0.91 g CuSO 4 = 63.5 + 32.1 + 4 x 16 = 159.6 g/mol CuSO 4 = 1.59 / 159.6 = 0.010 mol H 2 O = 2 x 1 + 16 = 18 g/mol H 2 O = 0.91 / 18 = 0.050 mol X = 0.050 / 0.010 = 5 CuSO 4 x 5H 2 O

6. What is the mole ratio of the hydrate CuSO4 x ___H2O, if the anhydrous mass of CuSO4 is 25.42g and mass of water is 14.3 g? CuSO 4 = 63.5 + 32.1 + 4 x 16 = 159.6 g/mol CuSO 4 = 25.42 / 159.6 = 0.159 mol H 2 O = 2 x 1 + 16 = 18 g/mol H 2 O = 14.3 / 18 = 0.79 mol X = 0.79 / 0.159 = 4.96 ~ 5 CuSO 4 x 5H 2 O 1:5

7. What is the mole ratio of hydrate Na 2 CO 3 x ____ H 2 O, if the original mass of the hydrated Na 2 CO 3 was 43.69 g and the mass of the anhydrous Na 2 CO 3 is 16.19g? Hydrate = anhydrous + H 2 O 43.69 = 16.19 + H 2 O H 2 O = 27.50 gNa 2 CO 3 = 16.19 g Na 2 CO 3 = 2 x 24.3 + 12 + 3 x 16 = 108.6 g/mol Na 2 CO 3 = 16.19 / 108.6 = 0.15 mol H 2 O = 2 x 1 + 16 = 18 g/mol H 2 O = 27.50 / 18 = 1.5 mol X = 1.5 / 0.15 = 10 Na 2 CO 3 x 10 H 2 O