1. Stoichiometry What’s that you said?

2. What is Stoichiometry? Stoichiometry is the numerical relationships in chemical reactions.

3. Let’s build a Tricycle (aka FSW 3 HP 2 ) For each tricycle we need : 1 frame (F) 1 seat (S) 3 wheels (W) 1 handlebar (H) 2 pedals (P) The “chemical equation” for building a tricycle would look like: F + S + 3W + H + 2P → FSW 3 HP 2

4. Tiny Tyke Workshop The Tiny Tyke workshop is scheduled to make 640 tricycles. How many wheels should be in the workshop to make these tricycles? Analyze the knowns and unknowns: Known: The # of tricycles we need to build = 640 tricycles Bal eq: F + S + 3W + H + 2P → FSW 3 HP 2 This balanced equation represents the formation of a single tricycle (FSW 3 HP 2 ) Therefore TT needs to make 640 FSW 3 HP 2

5. Unknown: number of wheels = ? Wheels 3 W 1 FSW 3 HP 2

6. We now solve for the unknown: 640 FSW 3 HP 2 3 W = 1920 W 1 FSW 3 HP 2 So you need 1920 wheels to make 640 tricycles. Does this make sense??

7. Tiny Tyke has decided to make 288 tricycles each day. How many seats, wheels and pedals are needed? Do this as 3 separate problems: Set up your ratios first: 1 S 3 W 2P 1 T 1 T 1 T Now plug in what you’re given: 288 trikes 1 seat = 288 seats 1T

8. 288 trikes 3 W = 864 wheels 1 T 288 trikes 2 P = 576 pedals 1 T

9. Based on chemical equations and the law of conservation of matter Must know the balanced chemical equation for the reaction we are studying first You can determine the quantities of reactants and products in a chemical reaction from reaction stoichiometry Stoichiometry

10. There are 4 types of reaction stoichiometry problems: 1. mole-mole problems: moles of A → moles of B 2. mole-mass problems: moles of A → moles of B → mass of B 3. mass –mole problems: mass of A → moles of A → moles of B 4. mass-mass problems: mass of A → moles of A → moles of B → mass of B What step do they all have in common?

11. Mole ratio The relationship between the number of moles of reactants and/or products in a chemical equation. N 2 (g) + 3 H 2 (g) → 2NH 3 (g) The mole ratio of H to N is 3 : 1 So… for every 1 mole of nitrogen, I need 3 moles of hydrogen (and will produce 2 moles of ammonia)

12. Now lets Pracitce In the Synthesis of water, if I start out with 42 grams of H 2 and an excess of 0 2, how much water will I have at the conclusion of the reaction?

13. 1. Write the equation H 2 + O 2  H 2 O 2. Balance the equation 2H 2 + O 2  2H 2 O 3. Start with what you know 4. 42 g H 2

14. Now its your Turn!

15. Butane (C 4 H 10 ) undergoes combustion. Balanced Equation: __ C 4 H 10 + __ O 2  __ CO 2 + __ H 2 O How many grams of CO 2 are produced when 88 g of O 2 are reacted with an excess of butane?