Youtube What I notice What I wonder Warm up #30

Formula of a Hydrate

HYDRATE An ionic compound that contains water molecules in its structure The formula states how many mol of water molecules per one mol of ionic compound Example: CuSo4  5 H20 Copper sulfate pentahydrate Na2CO310H2O Na2SO410H2O MgSO47H2O ZnSO47H2O

CuSo4  5 H20

ANHYDRATE The substance that remains after the water is removed from a hydrate Example: CuSo4 Anhydrous Copper sulfate

CuSo4

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

Steps to find formula Find the mass of anhydrate and water Convert mass of both anhydrate and water to moles, respectively Find the mole ratio of water to anhydrate Write the formula and name

Example 1 A calcium chloride hydrate has a mass of 4.72g. After heater for several minutes the mass of the anhydrate is found to be 3.56g. Determine the formula and name of the hydrate. Calcium chloride: Ca2+ Cl− CaCl2 Step 2: 4.72g hydrate − 3.56g anhydrate 1.16g H2O Step 3: 3.56g CaCl2 1mol CaCl2 110.98g CaCl2 1.16g H2O 1mol H2O 18.02g H2O = 0.0321 molCaCl2 = 0.0644 mol H2O SIG FIGS IN ANSWER MUST MATCH GIVEN!!

Step 4: Ratio 0.0644 mol H2O 2 0.0321 mol CaCl2 Step 5: CaCl2 2H2O Step 6: calcium chloride dihydrate ≈ 1

Example 2 A 15.67 g sample of a hydrate of magnesium carbonate was heated, without decomposing the carbonate, to drive off the water. The mass of the anhydrate was found to be 7.58 g. What is the formula and name of the hydrate?

Example 3 What is the formula an name for a hydrate which consists of 76.9% CaSO3 and 23.1% H2O?

Warm Up # 31 What is a hydrate? What is an anhydrate? If the anhydrate is 25.6% what is the % of the hydrate and the water? An ionic compound that contains water molecules in its structure The substance that remains after water is removed from a hydrate. % of the hydrate is 100% % of the water is 74.4%