1. Mass Measurements In Chemistry Calculating Formula Weight of Hydrates

2. Hydrates Certain ionic compounds trap water molecules in their structure when they form. These are known as HYDRATES. Hydrates are written in this manner: Compound Formula Dot Number of Water Molecules CuSO 4 5H 2 O Hydrates are named as: Compound Name, a Number Prefix for the number of water molecules, then the word Hydrate. When calculating the formula weight of a hydrate, just include the MASS OF THE NUMBER OF WATER MOLECULES in the total.

3. Practice Problem What would be the formula weight of Magnesium Chlorate Pentahydrate? Formula = Mg(ClO 3 ) 2  5H 2 O 1 mole Mg x 24.305 g= 24.305 g 2 moles Cl x 35.453 g= 70.906 g 6 moles O x 15.999 g= 95.994 g 10 moles H x 1.0079 g= 10.079 g 5 moles O x 15.999 g= 79.995 g 281.279 g/mole

4. PRACTICE PROBLEMS Complete the following FORMULA WEIGHT (MOLAR MASS) calculations ON YOUR OWN PAPER! 1. Find the FORMULA WEIGHT of Aluminum Sulfate, Al 2 (SO 4 ) 3. 2. What is the MOLAR MASS of Sucrose, C 12 H 22 O 11 ? 3. Find the FORMULA WEIGHT of: Lithium Potassium Permanganate Tetrahydrate LiK(MnO 4 ) 2 ● 4H 2 O 4. What is the MOLAR MASS of Ammonium Phosphate Dihydrate. (NH4) 3 PO 4 ●2H 2 0