Stoichiometry Ch 12 Stoichiometric Calculations A Proportional Relationships

Stoichiometry – Ch. 12 Stoichiometric Calculations

A. Proportional Relationships 2 1/4 c. flour 1 tsp. baking soda 1 tsp. salt 1 c. butter 3/4 c. sugar 3/4 c. brown sugar 1 tsp vanilla extract 2 eggs 2 c. chocolate chips Makes 5 dozen cookies. b. I have 5 eggs. How many cookies can I make? 5 eggs 5 doz. 2 eggs Ratio of eggs to cookies = 12. 5 dozen cookies

A. Proportional Relationships b Stoichiometry • mass relationships between substances in a chemical reaction • based on the mole ratio b Mole Ratio • indicated by coefficients in a balanced equation 2 Mg + O 2 2 Mg. O

B. Stoichiometry Steps 1. Write a balanced equation. 2. Identify known & unknown. 3. Line up conversion factors. • Mole ratio - moles • Molar mass - moles grams • Molarity moles liters soln • Molar volume - moles liters gas Core step in all stoichiometry problems!! 4. Check answer.

C. Molar Volume at STP 1 mol of a gas=22. 4 L at STP Standard Temperature & 0°C and 1 atm Pressure

C. Molar Volume at STP LITERS OF GAS AT STP Molar Volume (22. 4 L/mol) MASS IN GRAMS Molar Mass (g/mol) MOLES 6. 02 1023 particles/mol Molarity (mol/L) LITERS OF SOLUTION NUMBER OF PARTICLES

D. Stoichiometry Problems b How many moles of KCl. O 3 must decompose in order to produce 9 moles of oxygen gas? 2 KCl. O 3 2 KCl + 3 O 2 ? mol 9 mol O 2 2 mol KCl. O 3 3 mol O 2 9 mol = 6 mol KCl. O 3

D. Stoichiometry Problems b How many grams of KCl. O 3 are req’d to produce 9. 00 L of O 2 at STP? 2 KCl. O 3 2 KCl + 3 O 2 ? g 9. 00 L O 2 1 mol 2 mol 122. 55 O 2 KCl. O 3 g KCl. O 3 = 32. 8 g 22. 4 L 3 mol 1 mol KCl. O 3 O 2 KCl. O 3

D. Stoichiometry Problems b How many grams of silver will be formed from 12. 0 g copper? Cu + 2 Ag. NO 3 2 Ag + Cu(NO 3)2 12. 0 g ? g 12. 0 1 mol 2 mol 107. 87 g Cu Cu g Ag Ag 63. 55 1 mol g Cu Cu = 40. 7 g 1 mol Ag Ag

D. Stoichiometry Problems b How many grams of Cu are required to react with 1. 5 L of 0. 10 M Ag. NO 3? Cu + 2 Ag. NO 3 2 Ag + Cu(NO 3)2 ? g 1. 5 L 0. 10 M 1. 5. 10 mol 1 mol 63. 55 L Ag. NO 3 Cu g Cu = 4. 8 g 1 L Cu 2 mol 1 mol Ag. NO 3 Cu