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Modern Chemistry Chapter 9 Stoichiometry

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Title: Modern Chemistry Chapter 9 Stoichiometry

1
Modern Chemistry Chapter 9Stoichiometry
2
Modern Chemistry Chapter 9Stoichiometry

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.

3
Types of Stoichiometry Problems

mole to mole (Both the given and the unknown
quantities are amounts in moles.)
mole to mass (The given amount is in moles and
the unknown amount is in grams.)
mass to mole (The given amount is in grams and
the unknown amount is in moles.)
mass to mass (Both the given and the unknown
amount is in grams.)

4
Mole Ratio Molar Mass

mole ratio- A conversion factor that relates the
amounts in moles of any two substances involved
in a chemical reaction.
Found by using the coefficients in the balanced
formula equation of the reaction.

molar mass- Equal to the mass in grams of one
mole of an element or a compound.
Found by adding the individual element atomic
masses from the formula of the compound.

5
Section Review Problems

Do section review problems
1 through 4 on page 301 of the textbook.

6
Section Review page 301

1- The branch of chemistry that deals with mass
relationships in compounds and in chemical
reactions.
2 HgO ? 2 Hg O2
2- a) 2 mol HgO 2 mol HgO
2 mol Hg 1 mol O2
2 mol Hg 2 mol Hg
2 mol HgO 1 mol O2
1 mol O2 1 mol O2
2 mol HgO 2 mol Hg

7
Section Review page 301

3- It is used to convert moles of one substance
into moles of another substance.
4- The formula equation MUST be BALANCED so mole
ratios can be determined.

8
Using Conversion Factors

Amount coefficient amount of
of given x of unknown unknown
substance coefficient substance
in moles of known in moles
moles x mole ratio moles of
given unknown
Do practice problems 1 2 on page 306 of text.

9
Page 306 1

3 H2 N2 ? 2 NH3
6 mol H2 x 2 mol NH3 4mol NH3
3 mol H2

10
Page 306 2

2 KClO3 ? 2 KCl 3 O2
15 mol O2 x 2 mol KClO3 10 mol KClO3
3 mol O2

11
Chapter 9 quiz 1- mole to mole calculations

6 NaBr Mg3(PO4)2 ? 2 Na3PO4 3 MgBr2
Use the above balanced formula equation to solve
the following
1- 7.0 moles of NaBr will produce ? moles Na3PO4
2- 3.0 moles of Mg3(PO4)2 will yield ? moles
MgBr2
3- 0.5 moles of NaBr will react with ? moles
Mg3(PO4)2
4- 2.5 moles of NaBr will yield ? moles Na3PO4
5- 2.5 moles NaBr will produce ? moles MgBr2

12
6 NaBr Mg3(PO4)2 ? 2 Na3PO4 3 MgBr2

1- 7 mol NaBr x 2 mol Na3PO4 2.3 mol
Na3PO4
6 mol NaBr
2- 3 mol Mg3(PO4)2 x 3.0 mol MgBr2 9 mol
MgBr2
1 mol Mg3(PO4)2
3- 0.5 mol NaBr x 1 mol Mg3(PO4)2 0.083 mol
6 mol NaBr
4- 2.5 mol NaBr x 2 mol Na3PO4 0.83 mol
Na3PO4
6 mol NaBr
5- 2.5 mol NaBr x 3 mol MgBr2 1.25 mol
MgBr2
6 mol NaBr

13
Using Conversion Factors

amount of mass in
given x moles unknown x molar grams
of
substance moles known mass of unknown
in moles unknown substance
moles x mole x molar mass
of unknown
given ratio mass (in grams)
unknown
Do practice problems 1 2 on page 308 of the
textbook.

14
Page 308 1 2

2 Mg O2 ? 2 MgO
2.00 mol Mg x 2 mol MgO x 40.3 g MgO 80.6 g
MgO
2 mol Mg 1 mol MgO
6 CO2 6 H2O ? C6H12O6 6 O2
10 mol CO2 x 1 mol C6H12O6 x 180 g C6H12O6 300
g C6H12O6
6 mol CO2 1 mol C6H12O6

15
Chapter 9 Quiz 2- mole-mass problems

3 MgF2 Al2O3 ? 3 MgO 2 AlF3
Use the above balanced formula equation to answer
the following questions.
1- 2.0 mol MgF2 will yield ? grams of MgO
2- 4.0 mol of Al2O3 ? ? grams of AlF3
3- If 6.0 mol of MgO is produced, ? grams of
AlF3
4- 0.6 mol MgF2 ? ? grams of AlF3
5- 2.75 mol Al2O3 ? ? grams of MgO

16
3 MgF2 Al2O3 ? 3 MgO 2 AlF3

1- 2.0 mol MgF2 x 3 mol MgO x 40.3 g MgO
80.6 g
3 mol MgF2 1 mol MgO MgO
2- 4.0 mol Al2O3 x 2 mol AlF3 x 84.0 g AlF3
672.0g
1 mol Al2O3 1 mol AlF3 AlF3
3- 6.0 mol MgO x 2 mol AlF3 x 84.0 g AlF3
336 g AlF3
3 mol MgO 1 mol AlF3
4- 0.6 mol MgF2 x 2 mol AlF3 x 84.0 g AlF3
33.6 g AlF3
3 mol MgF2 1 mol AlF3
5- 2.75 mol Al2O3 x 3 mol MgO x 40.3 g MgO
332gMgO
1 mol Al2O3 1 mol MgO

17
Using Conversion Factors

mass (g) x 1 mol given x mol unknown
moles of
of given molar mass mol given
unknown
substance of given substance
grams x 1 x mole ratio moles unknown
molar mass
Do practice problems 1 2 on page 309 of the
textbook.

18
Practice problems page 309

2 HgO ? 2 Hg O2
125 g O2 x 1 mol O2 x 2 mol HgO 7.81 mol HgO
32 g O2 1 mol O2
125 g O2 x 1 mol O2 x 2 mol Hg 7.81 mol Hg
32 g O2 1 mol O2

19
chapter 9 quiz 3- mass-mole problems

Na2O CaF2 ? 2 NaF CaO
Use the above equation to solve the problems.
1- 156.1 grams of CaF2 ? ? mol CaO
2- 186 g Na2O ? ? mol NaF
3- 31 g Na2O ? ? mol CaO
4- 31 g Na2O ? ? mol NaF
5- A yield of 84 g NaF ? ? mol CaO

20
Na2O CaF2 ? 2 NaF CaO

1- 156.1 g CaF2 x 1 mol CaF2 x 1 mol CaO
2.00 mol CaO
78.1 g CaF2 1 mol CaF2
2- 186.0 g Na2O x 1 mol Na2O x 2 mol NaF
6.0 mol NaF
62 g Na2O 1 mol Na2O
3- 31.0 g Na2O x 1 mol Na2O x 1 mol CaO
0.5 mol CaO
62.0 g Na2O 1 mol Na2O
4- 31.0 g Na2O x 1 mol Na2O x 2 mol NaF
1.0 mol NaF
62.0 g Na2O 1 mol Na2O
5- 84.0 g NaF x 1 mol NaF x 1 mol CaO
1.0 mol CaO
42.0 g NaF 2 mol NaF

21
Chemistry Chapter 9- Stoichiometry Practice
Problems

2 NaF CaO ? Na2O CaF2
1- 4.5 moles of NaF will produce -?- moles of
Na2O ?
4.5 mol NaF x 1 mol Na2O/2 mol NaF 2.25
moles Na2O
2- 3.2 moles of CaO will produce -?- grams of
CaF2 ?
3.2 mol CaO x 1 mol CaF2/1 mol CaO x 78.1
g CaF2/mol CaF2 249.9 g CaF2

2 NaF CaO ? Na2O CaF2
3- 168.0 grams of NaF will produce -?- moles of
Na2O ?
168.0 /42.0 x 1 /2 2.0 mol Na2O
4- 112.2 grams of CaO will produce -?- moles of
CaF2 ?
112.2/56.1 x 1/1 2.0 mol CaF2

5- Calculate the molar mass of each of the
reactants products of the above balanced
formula equation. Use the molar masses in the
following problems.
a- AlN
(1 x 27.0) (1 x 14.0) 41.0 g/mol
b- Na2O
(2 x 23.0) (1 x 16.0) 62.0 g/mol
c- Al2O3
(2 x 27.0) (3 x 16.0) 102.0 g/mol
d- Na3N
(3 x 23.0) (1 x 14.0) 83.0 g/mol

2 AlN 3 Na2O ? Al2O3 2 Na3N
6- 82.0 grams of AlN will produce -?- moles of
Al2O3 ?
82.0/41.0 x 1/2 1.0 mol Al2O3
7- 164.0 grams AlN will produce -?- moles of
Na3N ?
164.0/41.0 x 2/2 4.0 mol Na3N

2 AlN 3 Na2O ? Al2O3 2 Na3N
8- 2.5 moles of Na2O will produce -?- grams of
Na3N ?
2.5 x 2/3 x 83.0 138.3 g Na3N
9- 0.75 moles of Na2O will produce -?- moles
of Al2O3 ?
0.75 x 1/3 0.25 mol Al2O3
10- 11.0 moles of Na2O will produce -?- grams
of Na3N ?
11.0 x 2/3 x 83.0 608.7 g Na3N

2 H2 O2 ? 2 H2O
11- 8.0 grams of H2 will react with -?- moles
of O2 ?
8.0/2.0 x 1/2 2.0 mol O2
12- 64.0 grams of O2 will produce -?- moles of
H2O ?
64.0/32.0 x 2/1 4.0 mol H2O
13- 0.25 moles of H2 will produce -?- moles of
H2O ?
0.25 x 2/2 0.25 mol H2O

2 H2 O2 ? 2 H2O
14- 1.5 moles of H2 will produce -?- grams of
H2O ?
1.5 x 2/2 x 18.0 27.0 g H2O
15- 14 moles of O2 will produce -?- moles of
H2O ?
14 x 2/1 28.0 mol H2O

28
Using Conversion Factors

mass (g) x 1 mol given x mol unknown x
molar mass unknown mass
of given molar mass mol given
1 mol unknown of un-
substance of given
known
grams x 1 x mole ratio x molar mass
mass of unknown
given molar mass
Do practice problems 1, 2, 3 on page 311 of
textbook.
Do section review problems 1 - 5 on page 311 of
textbook.

29
Practice problems page 311

NH4NO3 ? N2O 2 H2O
32 g N2O x 1 mol N2O x 1 mol NH4NO3 x 80 g
NH4NO3 60 g NH4NO3
44 g N2O 1 mol N2O 1 mol
NH4NO3

30
Chapter 9 quiz 4- mass-mass problems

Na2O CaF2 ? 2 NaF CaO
1- 124 g Na2O ? ? grams NaF
2- 124 g Na2O ? ? grams CaO
3- 234.3 g CaF2 ? ? g NaF
4- 234.3 g CaF2 ? ? g CaO
5- 84.0 g NaF ? ? g CaO

31
Na2O CaF2 ? 2 NaF CaO

1- 124 g Na2O x 1 mol Na2O x 2 mol NaF x
42.0 g NaF 168 g
62 g Na2O 1 mol Na2O 1 mol
NaF
2- 124 g Na2O x 1 mol Na2O x 1 mol CaO x
56.1 g CaO 112.2 g
62 g Na2O 1 mol Na2O 1 mol CaO
3- 234.3 g CaF2 x 1 mol CaF2 x 2 mol NaF x
42.0 g NaF 252 g
78.1 gCaF2 1 mol CaF2 1 mol NaF
4- 234.3 g CaF2 x 1 mol CaF2 x 1 mol CaO x
56.1 g CaO 168.3 g
78.1 gCaF2 1 mol CaF2 1 mol CaO
5- 84.0 g NaF x 1 mol NaF x 1 mol CaO x 56.1
g CaO 56.1 g
42.0 g NaF 2 mol NaF 1 mol CaO

32
The MOLE HILL

x mole ratio
moles known moles unknown
molar mass x molar mass
of known of unknown
mass of known mass of unknown

33
Stoichiometry Practice Problems

2 H2 O2 ? 2 H2O
1) 2.5 mol H2 x 1 mol O2 1.25 mol O2
2 mol H2
2) 2.5 mol H2 x 2 mol H2O 2.5 mol H2O
2 mol H2
3) 2.5 mol H2 x 1 mol O2 x 32 g O2 40 g O2
2 mol H2 1 mol O2
4) 2.5 mol H2 x 2 mol H2O x 18 g H2O 45 g
H2O
2 mol H2 1 mol H2O

34
Stoichiometry Practice Problems

2 H2 O2 ? 2 H2O
5) 16 g H2 x 1 mol H2 x 1 mol O2 4.0 mol O2
2 g H2 2 mol H2
6) 16 g H2 x 1 mol H2 x 2 mol H2O 8.0 mol H2O
2.0 g H2 2 mol H2
7) 16 g H2 x 1 mol H2 x 1 mol O2 x 32 g O2 128
g O2
2.0 g H2 2 mol H2 1 mol O2
8) 16 g H2 x 1 mol H2 x 2 mol H2O x 18 g H2O
144 g H2O
2.0 g H2 2 mol H2 1 mol H2O

35
Limiting Reactant Percentage Yield

limiting reactant is the reactant that limits the
amount of the other reactant that can combine and
the amount of product that can be formed in a
chemical reaction.
excess reactant is the substance that is NOT
completely used up in a chemical reaction.

36
Sample Practice Problems

See sample problem F on page 313 of textbook.
Do practice problems 1 on page 313.
See sample problem G on pages 314-315.
Do practice problems 1 2 on page 315.

37
QuickLAB

Do the QuickLAB titled Limiting Reactants in a
Recipe on page 316 of the textbook.
Yes, cooking IS chemistry!

38
Percentage Yield

theoretical yield is the maximum amount of
product that can be produced from a given amount
of reactant
actual yield of a product is the measured amount
of a product obtained from a reaction
percentage yield is the ratio of the actual yield
to the theoretical yield multiplied by 100
percentage yield actual yield x 100
theoretical yield

39
Problems

see sample problem H on pages 317-318 of textbook
Do practice problems 1 2 on page 318.
Do section review problems 1 - 4 on page
318.
Do critical thinking problems 37, 38, 39,
40 on pages 322 323.

40
Chapter 9 test review

20 multiple choice questions
definitions of composition reaction
stoichiometry
mole ratios their definition use
SI units of molar mass
identify mole ratio from balanced formula
equation
5 mole-mole problems
Definitions practical applications of excess
reactant limiting reactant
definitions practical applications of
theoretical yield, actual yield, yield

41
Honors Chemistry Chapter 9 Test Review

25 multiple choice
Know the definitions of reaction composition
stoichiometry, mole ratio, and units of molar
mass.
Know what mole ratio means and how it is used in
stoichiometry.
Determine mole ratio using balanced formula
equation. (2)
Perform mole to mole stoichiometric calculations
(4).
Perform mole to mass stoichiometric calculations
(1).
Perform mass to mole stoichiometric calculations
(1).
Perform mass to mass stoichiometric calculations
(1).
Know definitions and applications of limiting and
excess reactants.
Know the definitions applications of actual
yield, theoretical yield, and percent yield.