Chapter 9 Stoichiometry

Stoichiometry ___________________: deals with the mass relationships of _______________________. __________________: involves mass relationships between _______________________ in a chemical rxn. Ch. 9-2

Reaction Stoich _________: a conversion factor that relates the __________ of any two substances involved in a chemical rxn. Made from the ____________________________. Molar ratio = Coeff. Unknown Coeff. Given Ch. 9-3

0.75mol AgNO3 x 1mol Al(NO3)3 = 0.25mol Al(NO3)3 Type 1 Mole to Mole Ex. How many ________ of Al(NO3)3 are produced when __________ of AgNO3 react in this equation? 3AgNO3 + Al → Al(NO3)3 + 3Ag 0.75mol AgNO3 x 1mol Al(NO3)3 = 0.25mol Al(NO3)3 3mol AgNO3 Ch. 9-4

Practice 1) Now you try one... Iron will react with oxygen to produce Fe2O3. How many moles of Fe2O3 will be produced if 0.80 mol of Fe reacts? First step, figure out the equation~ _____________________ Ch. 9-5

Type 1 Mole to Mole Now balance the equation ~ ________________________ Now set up your proportion: Ch. 9-6

Type 2 Mole to Mass Ex. In _____________, plants use energy from the sun to produce _________, C6H12O6, and oxygen from the rxn of _____________________. What _______, in grams, of glucose is produced when _________ of water react with carbon dioxide. ______________________________ 6CO2 + 6H2O → C6H12O6 + 6O2 3.00 mol H2O x 1 mol C6H12O6 x 180.18 g C6H12O6 6 mol H2O 1 mol C6H12O6 = 90.1 g C6H12O6 Ch. 9-7

Practice What mass of carbon dioxide, in grams, is needed to react with 3.00 mol of water in the previous problem? __________________________ Ch. 9-8

Type 3 Mass to Moles Ex. The first step in the industrial manufacture of nitric acid is the catalytic oxidation of ammonia, ammonia reacts with oxygen to produce nitrogen monoxide and water. If the rxn is run using 824 g of ammonia and excess oxygen, how many moles of water are formed? ______________________________________ ____________________________ 824 g NH3 x 1 mol NH3 x 6 mol H2O = ______ mol H2O 17.04 g NH3 4 mol NH3 Ch. 9-9

Practice 3) Oxygen was discovered by Joseph Priestly in 1774 when he heated mercury II oxide to decompose it to form its constituent elements. How many moles of mercury II oxide are needed to produce 125 g of oxygen? Ch. 9-10

___________________________ Type 4 Mass to Mass Ex. How much LiOH is produced when 0.38g of Li3N reacts with H2O? Ammonia is also produced. Li3N + H2O → LiOH + NH3 ___________________________ 0.38gLi3N x 1mol Li3N x 3mol LiOH x 23.94g LiOH 34.83g Li3N 1molLi3N 1 mol LiOH = ________LiOH Ch. 9-11

Practice 4) Now you try one: What mass of sodium chloride is produced when chlorine reacts with 0.30g of sodium iodide? Ch. 9-12

Limiting Reactants ________________: the reactant that _______ the amount of other reactants that can combine _____________ that can ______ in a chemical rxn. _______________: the reactant that is ___________ completely in a rxn. Ch. 9-13

Limiting Reactants When doing limiting reactant problems, you do a __________________ for each reactant with ______________. The reactant that produces the smaller amount of product is the limiting reactant. Ch. 9-14

______________________________ Limiting Reactants Ex. ____________________ react to form zinc sulfide according to the following rxn: ______________________________ If 2.00 mol Zn are heated with 1.00 mol S8, identify the limiting reactant. How many moles of excess reactant remain? How many moles of product are formed? a) 2.00 mol Zn x 8 mol ZnS = ________ mol ZnS 8 mol Zn 1.00 mol S8 x 8 mol ZnS = _________mol ZnS 1 mol S8 _________________ 9-15

Limiting Reactants 8 Zn + S8 → 8 ZnS b) How many moles of excess reactant remain? c) How many moles of product are formed? 2.00 mol ZnS x 1 mol S8 = 0.25 mol S8 is used in the rxn, so 8 mol ZnS ________________________ left over c) 2.00 mol of ZnS are formed. 9-16

Practice Carbon reacts with steam to produce hydrogen and carbon monoxide. If 2.40 mol of carbon are exposed to 3.10 mol steam, identify the limiting reactant. How many moles of each product are formed? What mass of each product is formed? Ch. 9-17

Practice Carbon reacts with steam to produce hydrogen and carbon monoxide. If 2.40 mol of carbon are exposed to 3.10 mol steam, identify the limiting reactant. How many moles of each product are formed? What mass of each product is formed? C + H2O → H2 + CO Ch. 9-18

Percent Yield ______________: the ____________ amount of product that can be produced from a given amount of reactant. (_____________) _____________: the ______________ amount of a product obtained from a rxn. ___________________: the ratio of actual yield to theoretical yield multiplied by 100. Ch. 9-19

Percent Yield % Yield = ______________ Ex. Determine the percent yield for the reaction between 6.92g of K and 4.28g of O2 if 7.36 g of KO2 is produced. First find the _____________ by determining the limiting reactant: ___________________ Ch. 9-20

Percent Yield K + O2 →KO2 6.92g K x 1mol K x 1mol KO2 x 71.10g = _______ 39.10g K 1 mol K 1mol KO2 KO2 4.28g O2 x 1mol O2 x 1mol KO2 x 71.10g = _______ 32.00g O2 1mol O2 1mol KO2 KO2 O2 is the limiting reactant, the theoretical yield of KO2 is 9.51g. % Yield = _____________________ Ch. 9-21

Practice 6) Determine the percent yield for the reaction between 45.9g of NaBr and excess chlorine gas to produce 12.8g NaCl and and unknown quantity of bromine gas. 9-22

Chapter 9 The End!