modern chemistry chapter 9 stoichiometry sections 1-3 introduction to stoichiometry ideal...

Chapter 9 Section 1 Intro. Stoichiometry pages 299-303

Modern ChemistryModern ChemistryChapter 9Chapter 9

StoichiometryStoichiometry

Sections 1-3Introduction to Stoichiometry

Ideal Stoichiometric CalculationsLimiting Reactant and Percent Yield


Chapter 9 VocabularyChapter 9 Vocabulary• Composition Stoichiometry• Reaction Stoichiometry• Mole Ratio• Limiting Reactant• Excess Reactant• Actual Yield• Theoretical Yield• Percent Yield


Chapter 9 Section 1Chapter 9 Section 1Introduction to StoichiometryIntroduction to Stoichiometry


Definitions

• Composition stoichiometry deals with the mass relationships of elements in compounds.

• Reaction stoichiometry involves the mass relationships between reactants and products in a chemical reaction.

Chapter 9 Section 1 Intro. Stoichiometry pages 299-303p. xx

Sto

ichio

metr

y A

nim

ati

on

Sto

ichio

metr

y A

nim

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on


Definitions

• A mole ratio is a conversion factor that relates the amounts in moles of any two substances involved in a chemical reactionExample: 2Al2O3(l) 4Al(s) + 3O2(g)

Mole Ratios: 2 mol Al2O3 2 mol Al2O3 4 mol Al

4 mol Al 3 mol O2 3 mol O2


Usi

ng t

he M

ole

Rati

oU

sing t

he M

ole

Rati

o


Mole – Mole ExamplesMg(s) + 2HCl(aq) MgCl2(aq) + H2(g)

• If 2 mol of HCl react, how many moles of H2 are obtained?

• How many moles of Mg will react with 2 mol of HCl?

• If 4 mol of HCl react, how many mol of each product are produced?

• How would you convert from moles of substances to masses?


Convert

ing f

rom

gC

onvert

ing f

rom

g

mol

mol


Section 1 HomeworkSection 1 Homework

Page 301 #1-4

Chapter 9 Section 2 Ideal Stoichiometry pages 304-311

Chapter 9 Section 2Chapter 9 Section 2Ideal Stoichiometric Ideal Stoichiometric

CalculationsCalculations


Reactants ProductsMASS OF

SUBSTANCEGIVEN

MASS OF SUBSTANCE

WANTED

MOLES OF SUBSTANCE

GIVEN

MOLES OF SUBSTANCE

WANTED

MOLAR MASS

MOLAR MASS

MOLE RATIO


Tool BoxTool Box

GRAMSMOLESMOLAR MASS

MOLES MOLESMOLE RATIO

GRAMSmLDENSITY

MOLES PARTICLES6.02x1023

1000 g = 1kg1000 mL = 1L

1000 mg = 1g


KgmL mg

g

mgKg

gmL

L

MOLES

MOLES

L


Sample ProblemHow many kilograms of ethane are

required to react with excess oxygen to produce 8.70 L of carbon dioxide? The density of carbon dioxide gas at standard temperature is 1.799 g/L.

0.00535 kg


KgmL mg

mgKg

gmL

L

MOLES

L

g

MOLES


C2H6 (g) + O2 (g) CO2 (g) + H2O (g) + E

gg

MOLES MOLES

8.70L? Kg

L CO2x x x xx

kg C2H6

g CO2 mol CO2mol C2H6 g C2H6

L CO2 g CO2 mol CO2mol C2H6 g C2H6


C2H6 (g) + O2 (g) CO2 (g) + H2O (g) + E

gg

MOLES MOLES

8.70L? Kg

L CO2x x x xx

kg C2H6g CO2 mol CO2mol C2H6 g C2H6

L CO2 g CO2 mol CO2mol C2H6 g C2H6

MO

LAR

MA

SS

DEN

SIT

Y

MO

LAR

RA

TIO

MO

LAR

MA

SS

10

00

g=

1K

g


Sample Problem p. 306In photosynthesis, plants use energy from the sun

to produce glucose, C6H12O6, and oxygen from the reaction of carbon dioxide and water.

What mass, in grams, of glucose is produced when 3.00 mol of water react with carbon dioxide?

90.1 g C6H12O6

mol-mass


Sample Problem p. 310Tin (II) fluoride, SnF2, is used in some

toothpastes. It is made by the reaction of tin with hydrogen fluoride according to the following equation.Sn(s) + 2HF(g) SnF2(s) + H2(g)

How many grams of SnF2 are produced from the reaction of 30.00 g HF with Sn?

117.5 g SnF2

mass-mass.


Sample Problem p. 305In a spacecraft, the carbon dioxide exhaled by

astronauts can be removed by its reaction with lithium hydroxide, LiOH, according to the following chemical equation.

CO2(g) + 2LiOH(s) Li2CO3(s) + H2O(l)

How many moles of lithium hydroxide are required to react with 20 mol CO2, the average amount exhaled by a person each day?

40 mol LiOHmol-mol


Sample Problem p. 309The first step in the industrial manufacture

of nitric acid is the catalytic oxidation of ammonia.NH3(g) + O2(g) NO(g) + H2O(g) (unbalanced)

The reaction is run using 824 g NH3 and excess oxygen.a. How many moles of NO are formed?b. How many moles of H2O are formed?48.4mol NO; 72.5 mol

H2O mass-mol


ProblemMagnesium burns in oxygen to produce

magnesium oxide. How many grams magnesium will burn in the presence of 189 mL of oxygen? The density of oxygen is 1.429g/L.

0.410 g Mg

mL-g


ProblemLimestone, CaCO3, can be decomposed with

heat to form lime, CaO, and carbon dioxide. How many moles of lime would be formed from the decomposition of 20.1 kilograms of limestone?

201 moles CaO

Kg-mol.



Page 311 #1-5


Section 2 HomeworkSection 2 HomeworkProblem BankProblem Bank

Page 890-892 #176, 177, 179, 180, 184, 187, 190,

191, 192, 194, 196

Chapter 9 Section 3 Limiting Reactant pages 312-318

Chapter 9 Section 3Chapter 9 Section 3Limiting Reactant and Percent Limiting Reactant and Percent

YieldYield


Definitions• The limiting reactant is the reactant

that limits the amount of the other reactant that can combine and the amount of product that can form in a chemical reaction.

• The excess reactant is the substance that is not used up completely in a reaction.


S’mores• Given the bag o’ reactants find the number of

s’mores you could produce if the balanced equation is

• 2 Tg + 1 Mm 1 Sm

• Tg = Teddy Graham

• Mm = Minimarshmallow

• Sm = S’more


S’mores• What is the limiting reactant?

• What is the reactant in excess?

• What is the amount in excess ?

• What is the theoretical yield?

• What is the actual yield?

• What is the percent yield?


Sample Problem p. 313Silicon dioxide (quartz) is usually quite

unreactive but reacts readily with hydrogen fluoride according to the following equation.SiO2(s) + 4HF(g) SiF4(g) + 2H2O(l)

If 6.0 mol HF is added to 4.5 mol SiO2, which is the limiting reactant?

HF

mol & mol limiting


ProblemI need a problem that requires them to answer

these questions

a.Which compound is the limiting reactant?

b.What is the theoretical yield of product?

c.What is the reactant in excess, and how much remains after the reaction is completed?

8.940 x 1023 molecules

mass & mass, limiting, actual


ProblemI need another problem that requires them to

answer these questions


b.What is the theoretical yield of product?




Chapter 9 Section 3 Limiting Reactant pages 312-318p. xx

Lim

itin

g R

eact

ant

Lim

itin

g R

eact

ant



Page 318 #1 & 2


Definitions• The theoretical yield is the maximum

amount of product that can be produced from a give amount of reactant.

• The actual yield is the measured amount of product obtained from a reaction.

• The percentage yield is the ratio of the actual yield to the theoretical yield, multiplied by 100.

Chapter 9 Section 3 Limiting Reactant pages 312-318p. xx

Perc

ent

Yie

ldPerc

ent

Yie

ld


Sample Problem p. 317Chlorobenzene, C6H5Cl, is used in the

production of many important chemicals, such as aspirin, dyes, and disinfectants. One industrial method of preparing chlorobenzene is to react benzene, C6H6, with chlorine, as represented by the following equation.

C6H6 (l) + Cl2 (g) C6H5Cl (l) + HCl (g)

When 36.8 g C6H6 react with an excess of Cl2, the actual yield of C6H5Cl is 38.8 g.

What is the percentage yield of C6H5Cl?

73.2%mass-mass percent


ProblemHydrogen sulfide gas can be formed by the action

of HCl and FeS, forming FeCl2 as product. What is the theoretical yield in molecules of hydrogen sulfide if 130.5 g of FeS are mixed with 150.0 g of HCl? If the percent yield in the lab is 93.6% what is the actual yield?




ProblemBenzene, C6H6, is reacted with bromine, Br2, to produce bromobenzene, C6H5Br, and hydrogen bromide, HBr, as shown below. When 40.0 g of benzene are reacted with 95.0 g of bromine, 65.0 g of bromobenzene is produced.

C6H6 + Br2 C6H5Br + HBr


b.What is the theoretical yield of bromobenzene?


d.What is the percentage yield?Benzene, 80.4g, Br2 13.2g, 80.8%


Molarity• Molarity measures the concentration of

solutions. (aq)

• Molarity = moles / liter

3M =

3 mol1 L


ProblemWhen 20.0 mL of 0.90M solution of lithium nitrate

and 15.0 mL of 0.40M solution of calcium phosphate react, a precipitate is formed. The mass of the precipitate produced in the lab is 0.66 grams. What is the reactant in excess, the limiting reactant, the amount in excess, the theoretical yield and the percent yield.

0.69 grams theo.


Section 3 HomeworkSection 3 HomeworkProblem BankProblem Bank

Page 892-894 #201, 208, 214, 217, 219, 223, 226,

229, 232

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