CHAPTER 9 STOICHIOMETRY STOICHIOMETRY IS THE BRANCH OF CHEMISTRY THAT DEALS WITH: A) MASS RELATIONSHIPS OF ELEMENTS IN COMPOUNDS B) MASS RELATIONSHIPS BETWEEN REACTANTS AND PRODUCTS IN CHEMICAL REACTIONS. 1) COMPOSITION STOICHIOMETRY- DEALS WITH MASS RELATIONSHIP OF ELEMENTS IN COMPOUNDS. (Uses subscripts & Oxidation #’s) (LAW OF DEFINITE COMPOSITION & MULTIPLE PROPORTIONS) (Chap3) 2) REACTION STOICHIOMETRY- DEALS WITH MASS RELATIONSHIPS AMONG REACTANTS AND PRODUCTS IN A CHEMICAL REACTION (BALANCED EQUATIONS & CONSERVATION OF MASS)

4 TYPES OF REACTION-STOICHIOMETRY PROBLEMS 1) MOLE - MOLE, MOLES OF A -> MOLES OF B 2H2 + O2  2H2O 2 mols + 1 mol  2 mols 6 mols +__mols ____mols 2) MOLE - MASS, MOLES OF A -> MOLES OF B -> MASS OF B 2 mols + 1 mol  2 mols 6 mols + 3 mols __6__mols Mass of O2 ____and mass of water____ Mols of O2 x 32g = mass of O2 96g) 1 MOL Mols of water x 18g = mass of water (108g)

2 mols + 1 mol  2 mols 3) MASS-MOLE, MASS OF A -> MOLS OF A -> MOLS OF B 2H2 + O2  2H2O 2 mols + 1 mol  2 mols 28g OF Hydrogen produces _______mols of water 28g x 1mol x 2mol H20 = mols of water 2g 2mols H2 4) MASS-MASS, MASS A -> MOLES A -> MOLES B -> MASS OF B 28g of Hydrogen produces _______grams of water 28g x 1mol x 2mol H20 = mols of water x 18g 2g 2mols H2 1 mol water

CONVERSION FACTORS MOLAR MASS AND MOLE RATIO MOLE RATIO - CONVERSION FACTOR THAT RELATES # OF MOLES OF ANY 2 SUBSTANCES IN A REACTION *COEFFICIENTS Molar Mass – Mass of a mole, - Formula mass in grams

Solving Problems TO SOLVE REACTION STOICHIOMETRY PROBLEMS: 1. BALANCE EQUATION 2. DETERMINE WHAT IS GIVEN AND WHAT IS REQUIRED. (Read Problem) (GIVEN MOLES OR MASS - REQUIRED MOLES OR MASS) IF GIVEN MASS, # OF MOLES OF GIVEN MUST BE CALCULATED BY THE EQUATION: MASS # OF MOLS = MOLAR MASS 3. FROM EQUATION CALCULATE MOLE RATIOS 4. USE MOLE RATIOS TO FIND THE # OF MOLS REQUIRED.(Use Coefficients) 5. IF MASS OF REQUIRED CALCULATE USING THE SAME EQUATION # OF MOLS = MOLAR MASS OR MASS = # OF MOLS x MOLAR MASS

CONVERSION FACTORS MOLAR MASS AS CONVERSION FACTOR ARE: A 102g B) I MOL Al2O3 1 MOL Al2O3 102g C) 27g D) 1 MOL Al 1 MOL Al 27g E) ___32g__ F) 1 MOL OF O2 1 MOL OF O2 32g

CONVERSION FACTORS 2Al2O3 -> 4Al + 3O2 A) 2 MOLES OF ALUMINUM OXIDE OR B) 4 MOLES OF Al 4 MOLES OF ALUMINUM 2 MOLES OF Al2O3 C) 4 MOLS OF Al OR D) 3 MOLS OF O2 3 MOLS OF O2 4 MOLS OF Al E) 2 MOLS OF Al203 OR F) 3 MOLS OF O2 3 MOLS OF O2 2 MOLS OF Al2O THEREFORE IF GIVEN 13 MOLES OF Al2O3, HOW MANY MOLS OF Al WILL BE PRODUCED. 13 MOLES OF Al2O3 X 4 MOLS OF Al = 26 MOLS OF Al 2 MOLS OF Al2O3

THEREFORE, IF YOU WANTED THE MASS OF THE ALUMINUM PRODUCED IN THE PREVIOUS PROBLEM, YOU CALCULATE THE FOLLOWING 26 MOLS OF Al x 27g Al = 702g OF Al 1 MOL OF Al

9.2 IDEAL STOICHIOMETRY CALCULATIONS ASSUME COMPLETE CONVERSION OF ALL REACTANTS INTO PRODUCTS. 1) MOLE - MOLE CALCULATION - MOLES OF SUBSTANCE A -> MOLS OF B MOLES OF A x MOLE RATIO B -> MOLS OF B A 2) MOLE - MASS CALCULATION – MOLES OF A -> MOLS OF B -> MASS OF B MOLS OF A x MOLE RATIO B x MOLAR MASS OF B = MASS OF B

3) MASS - MOLE CALCULATION – MASS OF A -> MOL OF A -> MOLS OF B MASS OF A x MOLE RATIO OF B -> MOLS OF B MOLAR MASS OF A A 4) MASS - MASS CALCULATION – Mass A Mols A  Mols B  Mass B MASS OF A X MOLE RATIO B -> MOLS B X Molar Mass B ->Mass B MOLAR MASS OF A A