11/15/20131Mon, Nov 18• Lecture 20 (Change)– Information Given by Chemical Equations (9.1)– Mole‐Mole Relationships (9.2)• Questions we’ll answer:– What does a balanced equation tell us?– What is the maximum number of moles of product we can obtain from a reaction?Interpreting Chemical EquationsCO(g) + 2H2(g)  CH3OH(l)• A reaction results in the rearrangement of atoms in one or more reactants to produce one or more products.• What is this chemical equation telling us?11/15/20132Stoichiometry and Mole Ratios• Stoichiometry: the process of using a balanced chemical equation to determine the relative amounts of reactants and products involved in a reaction.• Since chemistry occurs at the particulate level, stoichiometric calculations must employ a particulate picture. Mole ratios allow us to convert from moles of one substance in a balanced equation to moles of a second substance in the equation. 2 H2O(l)  2 H2(g) + O2(g)2H2O(l)2H2(g)+ O2(g)4H2O(l)4H2(g)+ 2O2(g)4Mole Ratios• What if we wanted to know the number of moles of H2and O2produced from the decomposition of 5.8 mol of H2O?2H2O(l)  2H2(g) + O2(g)• We know the following:• We can represent these molar equivalencies as conversion factors:2 mol H2O 2 mol H21 mol O22 mol H2O2 mol H2O 2 mol H2~2 mol H2O2 mol H21 mol H2O1 mol H2=2 mol H2O 1 mol O2~2 mol H2O1 mol O211/15/201335Mole Ratios• Now we can answer the question…How many moles of H2and O2are produced from the decomposition of 5.8 mol of H2O?2H2O(l)  2H2(g) + O2(g)1 mol H2O1 mol H25.8 mol H2O? mol H2=5.8 mol H2=2 mol H2O1 mol O25.8 mol H2O? mol O2=2.9 mol O2=Sodium fluorosilicate (Na2SiF6) is used in metallurgy, water fluoridation, and other applications. When sodium fluorosilicate is reacted with sodium metal, the silicon is reduced to its elemental form. The other product of this reaction is solid sodium fluoride. How many moles of NaF will be produced if 3.50 moles of Na is reacted with excess Na2SiF6? Na2SiF6(s) + Na(s) → Si(s) + NaF(s)Example11/15/20134Example. Propane, C3H8, is a common fuel used in heating homes in rural areas. Predict how many moles of CO2are formed when 3.74 moles of propane are burned in excess oxygen according to the equation:C3H8+ O2→ CO2 + H2OHow many moles of O2were consumed in the reaction? Example. Consider the following reaction:6 C(s) + 2 B2O3(s)  B4C3(s) + 3 CO2(g)If 2.43 mol of carbon dioxide were produced in the reaction, how many mol of carbon and diboron trioxide must have reacted?11/15/20135Example. One method of producing nitric acid (HNO3) involves a three step process:1. 4 NH3(g) + 5 O2(g)  4 NO(g) + 6 H2O(g)2. 2 NO(g) + O2(g)  2 NO2(g)3. 3 NO2(g) + H2O(l)  2 HNO3(aq) + NO(g)How much HNO3can be produced from 16.37 mol