1. Chapter 12- Stoichiometry

2. What is stoichiometry? “stochio” = Greek for element “metry” = measurement Converting a known quantity of one substance into an unknown quantity of another substance using a BALANCED EQUATION Interpreting a balanced equation: N 2 + 3 H 2  2 NH 3 Coefficients represent moles or representative particles. (We will use moles) 1 mole N 2 + 3 moles H 2 yields 2 moles NH 3

3. Mole Ratios Heart of stoichiometry; must be used in EVERY calculation you do Ratio of any two substances from balanced equation Example: N 2 + 3 H 2  2 NH 3

4. Write all mole ratios for: 3 NO 2 + H 2 O  2HNO 3 + NO

5. Analogy Think of a balanced equation as a recipe. Ex: Making a turkey and cheese sandwich 2 slices of bread + 3 slices of turkey + 1 slice of cheese  1 sandwich How could you make two sandwiches? How could you make ½ of a sandwich?

6. Stoichiometry Question 1 4NH 3 + 5O 2  6H 2 O + 4NO How many moles of H 2 O are produced if 2.00 moles of O 2 are used?

7. Stoichiometry Question 2 4NH 3 + 5O 2  6H 2 O + 4NO How many moles of NO are produced in the reaction if 15 mol of H 2 O are also produced?

8. Mole Bridge

9. 4 NH 3 + 5 O 2  6 H 2 O + 4 NO MOLE RATIO (coefficients)

10. 4 NH 3 + 5 O 2  6 H 2 O + 4 NO How many grams of H 2 O are produced if 2.2 mol of NH 3 are combined with excess oxygen? Stoichiometry Question 3 MOLE RATIO (coefficients) (H 2 O) (NH 3 )

11. 4 NH 3 + 5 O 2  6 H 2 O + 4 NO How many grams of H 2 O are produced if 2.2 mol of NH 3 are combined with excess oxygen? Stoichiometry Question 3

12. Stoichiometry Question 4 4 NH 3 + 5 O 2  6 H 2 O + 4 NO How many grams of NO are produced if 12 g of O 2 is combined with excess ammonia?

13. Moving along the stoichiometry path We always use the same type of information to make the jumps between steps: grams (x)  moles (x)  moles (y)  grams (y) Molar mass of xMolar mass of y Mole ratio from balanced equation

14. Practice! Try these on your own - 4 NH 3 + 5 O 2  6 H 2 O + 4 NO a) How many moles of H 2 O can be made using 1.6 mol NH 3 ? b) What mass of NH 3 is needed to make 0.75 mol NO? c) How many Liters of NO can be made from 47 g of NH 3 ?