1. Mass-Gas Stoichiometry Using a balanced chemical equation, it is possible to determine the volume of a gas if the mass of a reactant or product Is given. This mass-volume stoichiometry.

2. Mass-Gas Stoichiometry In mass-volume stoichiometry it is Necessary to use the molar volume of a gas. One mole of any gas at STP (Standard Temperature and Pressure, 101.3 kPa and 273 K) occupies a volume of 22.4 L. So You will use 1 mole = 22.4 L as your last conversion unit instead of the formula mass.

3. C 8 H 18 + O 2 → CO 2 + H 2 O Step 1: Balance the chemical equation 161825 3.59 g ? Sample Problem: How many liters (at STP) of carbon dioxide, CO 2, will be produced in the following reaction if 3.59 g of oxygen, O 2, is consumed during combustion of octane, C 8 H 18 ? 2

4. 3.59 g ? 2C 8 H 18 + 25O 2 → 16CO 2 + 18H 2 O Step 2: Convert grams of given substance to moles 3.59 g O 2 1 mol O 2 32.0 g O 2 Step 3: Give ratio of moles required gas/moles of given substance 16 mol CO 2 25 mol O 2 Step 4: Convert moles of required gas to liters 22.4 L CO 2 1 mol CO 2 Step 5: Cancel and solve = 1.61 L CO 2

5. Practice problems Try to work the next problems on the paper first. Then use the power point to check your work.

6. 10.0 g ? H 2 O  H 2 + O 2 Solve the above problem and check your answer below: 10.0 g H 2 O 1 mol H 2 O 18.0 g H 2 O 1 mol O 2 2 mol H 2 O 22.4 L O 2 1 mol O 2 =6.22 L O 2 Practice Problem 1: What volume of oxygen (O 2 ) at STP is produced during the electrolysis of 10.0 g H 2 O in the equation given below? 22

7. 3.88g ? BaCl 2 + Br 2  BaBr 2 + Cl 2 Solve the problem and then check your answer below. 3.88 g BaCl 2 1 mol BaCl 2 208 g BaCl2 2 1 mol Cl 2 _ 1 mol BaCl 2 22.4 L Cl 2 1 mol Cl 2 = 0.418 L Cl 2 Practice Problem 2: What is the volume of chlorine at STP released during the following reaction by 3.88 grams of barium chloride assuming an excess of bromine (Br 2 )?

8. 32.0 ? H 2 + N 2  NH 3 Solve the problem and then check your answer below. 32.0 g H 2 1 mol H 2 2.02 g H 2 2 mol NH 3 3 mol H 2 22.4 L NH 3 1 mol NH 3 =237 L NH 3 Practice Problem 3: What volume of ammonia (NH 3 ) at STP will be produced by 32.0 grams of hydrogen (H 2 ) reacting with an excess of nitrogen (N 2 ) in the following reaction? 32