1. Stoichiometry and the Math of Equations Part 2: Mass-Volume

2. Objectives -Determine the molar relationships between reactants and products in a reaction equation -Use molar relationships and molar volume to convert between mass and volumes of components in a reaction 2

3. Equations Equations are quantitative-there is a mathematical relationship between reactants and products a) mass-mass problems b) mass-volume problems c) volume-mass problems d) volume-volume problems 3

4. Molar Volume Molar volume- the volume of 1 mole of ANY gas –Directly related to the number of gas molecules –1 mole of any gas contains the same number of molecules (6.02  10 23 ) so the volume of 1 mole of any gas is the same volume! 22.4 liters! 4

5. Molar Volume The volume of one mole is affected by temperature and pressure changes –Assume we’re working under standard conditions of temp and pressure, called STP, which is T =273 K (0° Celsius) and P =1 atm pressure Conversion factors: 22.4 liters OR 1 mole 1 mol 22.4 liters 5

6. Molar Volume Problem #1 Mass – Volume How many liters of hydrogen will combine with 10.0 grams of oxygen to make water vapor? Steps (1) write and balance the equation (2) indicate the given and required (3) indicate the mole relationship between the given and the required below the equation 6

7. How many liters of hydrogen will combine with 10.0 grams of oxygen to make water vapor? Steps (1-3) ? L 10.0 g 2 H 2 + O 2  2 H 2 O 2 mole 1 mole ? L H 2 = Step (4) 10.0 g O 2 x 1 mol O 2 x 2 mol H 2 x 22.4 L H 2 1 32.0 g O 2 1 mol O 2 1 mol H 2 = 14.0 L H 2 7

8. Molar Volume Problem #2 Volume – Mass How many grams of hydrogen will combine with 15 liters of oxygen to make water vapor? Steps (1-3) ? g 15 L 2 H 2 + O 2  2 H 2 O 2 mole 1 mole 8

9. How many grams of hydrogen will combine with 15 liters of oxygen to make water vapor? Step (4) ? g H = 15L O 2 x 1 mol O 2 x 2 mol H 2 x 2.02g H 2 = 1 22.4 L O 2 1 mol O 2 1 mol H 2 = 2.7 g H 2 9

10. Molar Volume Problem #3 Volume-Volume How many liters of water vapor can be made if 5.0 liters of hydrogen combine with oxygen? Steps (1-3) 5.0L ? L 2 H 2 + O 2  2 H 2 O 2 mole 10

11. How many liters of water vapor can be made if 5.0 liters of hydrogen combine with oxygen? Step (4) ? L H 2 O = 5.0 L H 2 x 1 mol H 2 x 2 mol H 2 O x 22.4 L H 2 O 1 22.4 L H 2 2 mol H 2 1 mol H 2 O = 5.0 L H 2 O 11

12. Objectives -Determine the molar relationships between reactants and products in a reaction equation -Use molar relationships and molar volume to convert between mass and volumes of components in a reaction 12