I. I.Stoichiometric Calculations Stoichiometry

A. Proportional Relationships b Having everything I need for making cookies. I have 5 eggs. How many cookies can I make? 3/4 c. brown sugar 1 tsp vanilla extract 2 eggs 2 c. chocolate chips Makes 5 dozen cookies. 2 1/4 c. flour 1 tsp. baking soda 1 tsp. salt 1 c. butter 3/4 c. sugar 5 eggs5 doz. 2 eggs = 12.5 dozen cookies Ratio of eggs to cookies

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

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

C. The Mole Hill Mole Ratio Molar Mass X Molar Mass Y Grams of X Grams of Y

C. Moles of X to Moles of Y 1. How many moles of H 2 O are produced from 10 moles of O 2 gas? 10 mol O 2 2 mol H 2 O 1 mol O 2 = 20 moles H 2 O 2H 2 + O 2  2H 2 O 10 mol? mol Mole Ratio

b Day 2

C. Moles of X to Grams of Y How many grams of NaOH are produced from 5 moles of Na? 2H 2 O + 2Na  2 NaOH + H 2 5 mol ? grams 5 mol Na 2 mol Na 2 mol NaOH 1 mol NaOH g NaOH Mole Ratio Formula Mass g NaOH = STEP 1 STEP 2

C. Grams of X to Moles of Y How many moles of water are produced from 5 grams of oxygen gas? 4 NH 3 (g) + 5O 2 (g)  4NO(g) + 6H 2 O(g) 5 g ? moles 5 g O g O 2 1 mol O 2 5 mol O 2 6 mol H 2 O = 0.19 mol H 2 O Mole Ratio Formula Mass STEP 1 STEP 2

b Day 3

C. Grams of X to Grams of Y How many grams of MgO are produced from 145 g of Mg? 2 Mg + O 2  2 MgO 145 g ? g 145 g Mg 24.31g Mg 1 mol Mg 2 mol Mg 2 mol MgO 1 mol MgO g MgO Mole Ratio = g MgO STEP 1 STEP 2 STEP 3

Molar Mass (g/mol) 6.02  particles/mol MASS IN GRAMS MOLES NUMBER OF PARTICLES LITERS OF SOLUTION Molar Volume (22.4 L/mol) LITERS OF GAS AT STP Molarity (mol/L)

Practice Problems

D. Stoichiometry Practice 1. How many moles of KClO 3 must decompose in order to produce 9 moles of oxygen gas? 9 mol O 2 2 mol KClO 3 3 mol O 2 = 6 mol KClO 3 2KClO 3  2KCl + 3O 2 ? mol9 mol

D. Stoichiometry Practice 3.How many grams of silver will be formed from 12.0 g copper? 12.0 g Cu 1 mol Cu g Cu = 40.7 g Ag Cu + 2AgNO 3  2Ag + Cu(NO 3 ) 2 2 mol Ag 1 mol Cu g Ag 1 mol Ag 12.0 g? g