1. Stoichiometry

2. Stoichiometry is the study of the mass relationships of the reactants and the products in a chemical reaction. How much stuff it takes to make a certain amount of new stuff. Based on the law of conservation of mass Mass of the reactants must equal the mass the products CH 3 OH (g) + O 2(g)  CO 2(g) + H 2 O (g)

3. Chemical reactions are mole ratios between the reactants and the products – not a mass ratio! Mole ratio – the ratio of moles of any two substances in a chemical reaction 2CH 3 OH (l) + 3O 2(g)  2CO 2(g) + 4H 2 O (g) 2 mol CH 3 OH : 2 mol CO 2 3 mol O 2 : 4 mol H 2 O There is not a direct relationship between masses of individual reactants and products. Must use the mole ratio to convert!

4. R1 + R2 → P1 + P2 grams grams molar mass molar mass R1 P2 moles R1 moles P2 moles P2 moles R1 (mole ratio)

5. Guidelines for Stoichiometry 1. Write a balanced equation for the chemical reaction. 2. Convert grams A to moles of A using the molar mass. 3. Convert moles of A to moles of B using the mole ratio. 4. Convert moles of B to grams of B using the molar mass.

7. 3. Examples 24.Sulfuric acid reacts with sodium hydroxide to form sodium sulfate and water. How many grams of Na 2 SO 4 are produced from 25.0 g of H 2 SO 4 ?

8. 25.In the reaction from #24, I need 550.0 g Na 2 SO4. What mass of each reactant is required?

9. 26.How much oxygen will be required to react with 100.0 g KCl to produce KClO 3.

10. 27.What mass of hydrogen peroxide must decompose to produce 0.77 g of water? The other product is oxygen gas.

11. 28.Space vehicles use solid lithium hydroxide to remove exhaled carbon dioxide according to the equation: LiOH + CO 2  Li 2 CO 3 + H 2 O. Determine the mass of carbon dioxide removed if the space vehicle carries 1.00 kg of LiOH.

12. 29.How many grams of carbon dioxide are produced when 2.50 g of baking soda react with excess citric acid (H 3 C 6 H 5 O 7 ) to produce Na 3 C 6 H 5 O 7, carbon dioxide, and water.

13. 30.Aspirin (C 9 H 8 O 4 ) is produced when salicylic acid (C 7 H 6 O 3 ) reacts with acetic anhydride (C 4 H 6 O 3 ) according to the equation C 7 H 6 O 3 + C 4 H 6 O 3  C 9 H 8 O 4 + HC 2 H 3 O 2. Determine the mass of aspirin produced when 150.0 g of salicylic acid reacts with an excess of acetic anhydride.