The document outlines the basics of writing and balancing chemical equations, including identifying the reactants and products, determining the appropriate coefficients, and accounting for atoms. It also describes the different types of chemical reactions such as combination, decomposition, single displacement, and double displacement reactions. Key reaction examples are provided for each type.

1. Chapter 8
Chemical Equations
Flames and
sparks result
when aluminum
foil is dropped
Into liquid
bromine.
Introduction to General, Organic, and Biochemistry 10e
John Wiley & Sons, Inc
Morris Hein, Scott Pattison, and Susan Arena

2. Chapter Outline
8.1 The Chemical Equation
8.2 Writing and Balancing Chemical Equations
8.3 Information in a Chemical Equation
8.4 Types of Chemical Equations
8.5 Heat in Chemical Reactions
8.6 Global Warming: The Greenhouse Effect
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3. The Chemical Equation
Chemical shorthand for a chemical reaction.
4Al(s) + 3O2(g) 2Al2O3(s)
1. Reactants  Products
2. Whole number coefficients indicate numbers of each
substance participating in the reaction.
3. Special conditions for the reaction are often written
over the arrow. (Δ means heat is supplied to the
reaction.)
4. Physical states of each substance are indicated.
Review Question 1: Purpose of balancing2012 John Wiley & Sons, Inc
Copyright
chemical reaction?

4. The Chemical Equation
Review Question 6
Mg(s) + 2HCl(aq) H2(g) + MgCl2(aq)
NaOH(aq) + HCl(aq) H2O(l) + NaCl(aq)
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5. Your Turn!
In the reaction: CuSO4 + BaBr2 CuBr2 + BaSO4
a. BaBr2 and BaSO4 are reactants
b. BaSO4 and CuBr2 are products
c. CuSO4 and BaSO4 are reactants
d. CuSO4 and BaBr2 are products
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6. Writing and Balancing R = reactants
Chemical Equations P = products
A balloon filled with a hydrogen and oxygen gas
explodes when heated. The product is water vapor.
1. Identify the reaction
Hydrogen gas + oxygen gas  water gas
2. Write the unbalanced equation
H2(g) + O2(g)  H2O(g)
3. Balance the equation R 2H 2O
R 4H 2O
2 H2(g) + O2(g)  2 H2O(g) P 2H 1O
4
P 4H 2O2O
A balanced equation has the same number of each kind
of atom on each side of the equation.
Review Question 2: What do the numbers in John Wiley & Sons, Inc
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front represent?

7. Writing and Balancing
Chemical Equations
Phosphorus burns in air to produce diphosphorus
pentoxide.
1. Identify the reaction
phosphorus + oxygen  diphosphorus pentoxide
2. Write the unbalanced equation
P4 + O2  P2O5
3. Balance the equation
R 4P 10 O
2O
P4 + 5 O2  2 P2O5
P 2P
4 10 O
5O
Hint: Start with most complex compound.
Review Question 5: How do
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you account for the atoms?

8. Your Turn!
Given the unbalanced equation:
HCl + NH3  NH4Cl
When properly balanced, the sum of the balancing
coefficients is
a. 7
b. 5 HCl + NH3  NH4Cl
c. 3
d. 4
e. 6
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9. Your Turn!
Given the unbalanced equation:
NH3  H2 + N2
When properly balanced, the sum of the balancing
coefficients is
a. 3
b. 6 2NH3  3H2 + N2
c. 9
d. 12
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10. Writing and Balancing
Chemical Equations
Zinc metal reacts with silver nitrate to produce zinc
nitrate and silver metal.
1. Identify the reaction
zinc + silver nitrate  zinc nitrate + silver
2. Write the unbalanced equation
Zn + AgNO3  Zn(NO3)2 + Ag
3. Balance the equation
R 1 Zn 1 Ag 1 NO3
2 2
Zn + 2AgNO3  Zn(NO3)2 + 2 Ag
P 1 Zn 1 Ag 2 NO3
2
Hint: Balance polyatomic ions as a unit.
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11. *Your Turn!
Given the unbalanced equation:
Co + CuSO4 Co2(SO4)3 + Cu
When properly balanced, the sum of the balancing
coefficients is
a. 6
b. 7 2Co + 3CuSO4 Co2(SO4)3 + 3Cu
c. 8
d. 9
e. 10
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12. Your Turn!
Given the unbalanced equation:
Al(OH)3 + H2SO4 Al2(SO4)3 + H2O
When properly balanced, the sum of the balancing
coefficients is
a. 4
b. 9 2Al(OH)3 + 3H2SO4 Al2(SO4)3 + 6H2O
c. 12
d. 24
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13. Writing and Balancing
Chemical Equations
Ethylene burns in air to produce carbon dioxide and
water.
1. Identify the reaction
ethylene + oxygen  carbon dioxide + water
2. Write the unbalanced equation
C2H4 + O2  CO2 + H2O
3. Balance the equation
R 2C 4H 6
2O
C2H4 + 3 O2 2 CO2 + 2 H2O P 1C
2 4
2H 4+2
4+1
2+1 O
Hint: Balance hydrogen and oxygen last.
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14. Acetylene (C2H2) burns in air to produce carbon
dioxide and water.
1. Identify the reaction
acetylene + oxygen  carbon dioxide + water
2. Write the unbalanced equation
C2H2 + O2  CO2 + H2O
3. Balance the equation R 2C
4 4
2H 10
5 O
2O
5 P 1C
4C
2 4
2H 8+2
4+1
2+1 O
2(C2H2 + O2 2 CO2 + H2O )
2
Hint: Use a fraction to balance O, then multiply all
coefficients by two to eliminate the fraction.
2 C2H2 + 5 O2  4 CO2 + 2 H2O
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15. Your Turn!
Given the unbalanced equation:
C2H6 + O2 CO2 + H2O
When properly balanced, the sum of the balancing
coefficients is
a. 23
b. 19 2C2H6 + 7O2 4CO2 + 6H2O
c. 17
d. 9
e. 13
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16. Your Turn!
Given the unbalanced equation:
C3H8 + O2 CO2 + H2O
When properly balanced, the sum of the balancing
coefficients is
a. 7
b. 9 C3H8 + 5O2 3CO2 + 4H2O
c. 15
d. 23
e. 13
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17. Information in a Chemical Equation
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18. Information in a Chemical Equation
H2(g) + F2(g)  2HF(g)
1 molecule 1 molecule 2 molecules
2 atoms H 2 atoms F 2 atoms H + 2 atoms F
1 mol H2 1 mol F2 2 mol HF
How many moles of HF can be made from 2 moles of
hydrogen gas and 2 moles of fluorine gas?
4 moles of hydrogen fluoride gas
What is conserved?
Atoms!
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Review Question 3

19. Your Turn!
How many molecules of oxygen gas are needed to burn
2 molecules of propane according to the balanced
equation ? C3H8 + 5O2 3CO2 + 4H2O
a. 5 molecules of oxygen
b. 6 molecules of oxygen
c. 10 molecules of oxygen
d. 15 molecules of oxygen
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20. Types of Chemical Equations
1. Combination Reactions
A+B AB
2. Decomposition Reactions
AB A+B
3. Single-Displacement
A + BC B + AC or A + BC C + BA
4. Double-Displacement
A B+ CD AD + CB
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21. Combination Reactions
1. metal + oxygen  metal oxide A+B AB
2Mg(s) + O2(g)  2MgO(s)
4Fe(s) + 3O2(g)  2Fe2O3(s)
2. nonmetal + oxygen  nonmetal oxide
C(s) + O2(g)  CO2(g)
2N2(s) + O2(g)  2N2O (g)
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22. Combination Reactions
3. metal + nonmetal  salt A+B AB
2Al(s) + 3Br2(l)  2AlBr3(s)
2K(s) + I2(s)  2KI(s)
4. metal oxide + water  metal hydroxide
K2O(s) + H2O(l)  2KOH(aq)
SrO(s) + H2O(l)  Sr(OH)2(aq)
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23. Combination Reactions
5. nonmetal oxide + water  oxy-acid A+B AB
SO3(g) + H2O(l)  H2SO4(aq)
P2O5(s) + 3H2O(l)  2H3PO4(aq)
N2O5(s) + H2O(l)  2HNO3(aq)
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24. Decomposition Reactions
1. Metal oxides decompose into metals and oxygen gas.
2HgO(s) 2Hg(l) + O2(g) AB A+B
2PbO2(s) 2PbO(s) + O2(g)
2. Metal carbonates form metal oxides and CO2.
Na2CO3(s) Na2O + CO2(g)
3. Metal bicarbonates form metal carbonates, CO2 and
H2O.
NaHCO3(s) Na2CO3(s) + CO2(g) + H2O(g)
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25. Decomposition Reactions
4. Other examples: AB A+B
2Hg2O2(aq) 2H2O(l) + O2(g)
2NaClO3(s) 2NaCl(s) + 3O2(g)
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26. Single Displacement Reactions
If A is a metal: A + BC B + AC
If A is a nonmetal: A + BC C + BA
Zn(s) + 2HCl(aq) ZnCl2(aq) + H2(g)
When pieces of zinc metal are placed
in hydrochloric acid, hydrogen
bubbles form immediately.
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27. Activity Series
Review Question 7 a
More active elements can replace less
active elements.
2Al(s) + 3CuCl2(aq) 2AlCl3(aq) +73Cu (s)
Review Question b
Hg(l) + CuSO4(aq) no reaction
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28. Your Turn!
Consider the following reactions:
A(s) + HCl(aq)  no reaction
B(s) + 2HCl(aq)  BCl2(aq) + H2(g)
What is the correct activity series?
a. least active A < B < H most active
b. least active A < H < B most active
c. least active B < H < A most active
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29. Single Displacement Reactions
1. Metal + acid  H2 + salt
Fe(s) + 2HCl(aq) FeCl2(aq) + H2 (g)
Cu(s) + HCl(aq)  no reaction
2. metal + water  H2 + metal oxide
or metal hydroxide
2K(s) + 2H2O(l) 2KOH(aq) + H2 (g)
3Fe(s) + 4H2O(g) Fe3O4(s) + 4H2 (g)
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30. Single Displacement Reactions
3. Metal + salt  metal + salt
Sn(s) + 2AgNO3(aq) Sn(NO3)2(aq) + Ag(s)
Zn(s) + AlCl3(aq)  no reaction
4. halogen + halide salt halogen +
halide salt
F2(g) + 2NaCl(aq) 2NaF(aq) + Cl2 (g)
I2(s) + 2NaCl(aq) no reaction
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31. Your Turn!
The reaction: Ba(s) + PtCl2(aq) BaCl2(aq) + Pt(s), will
occur if
a. Pt is more active than Ba
b. Ba is more active than Pt
c. Ba is more active than O
d. O is more active than Pt
Copyright 2012 John Wiley & Sons, Inc

32. Your Turn!
The likely products of the reaction
between Al and NiCl2 are
a. AlNi and Cl2
b. AlCl2 and Ni
c. AlCl and Ni
d. AlCl3 and Ni
e. no reaction
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33. Double Replacement Reactions
A B+ CD AD + CB
Cations exchange anions
Pb(NO3)2(aq) + 2KI(aq)  PbI2(s) + 2KNO3(aq)
Evidence of chemical change:
1. Evolution of heat
2. Formation of precipitate
3. Formation of gas bubbles
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34. Neutralization Reactions
Double replacement: A B+ CD AD + CB
acid + base  salt + water + heat
HCl(aq) + NaOH(aq)  NaCl(aq) + H2O(l)
Detected by increase in temperature (release of heat).
H2SO4(aq) + Ba(OH)2(aq)  BaSO4(s) + 2H2O(l)
Detected by increase in temperature and formation of a
cloudy precipitate.
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35. Metal Oxide + Acid Reactions
Double replacement: A B+ CD AD + CB
metal oxide + acid  salt + water
Heat is released by the production of water
ZnO(s) + 2HCl(aq)  ZnCl2(aq) + H2O(l)
Na2O(s) + 2HCl(aq)  2NaCl(aq) + H2O(l)
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36. Precipitation Reactions
Double replacement: A B+ CD AD + CB
An insoluble product (precipitate) is formed
and indicated by placing an (s) after its
formula in the equation.
Check the solubility table in Appendix V to
see if a precipitate forms.
BaCl2(aq) + Na2SO4(aq) BaSO4(s) + 2NaCl(aq)
2NaCl(aq) + Hg2(NO3)2(aq) 2NaNO3(aq) + Hg2Cl2(s)
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37. Gas Forming Reactions
Double replacement: A B+ CD AD + CB
NaCl(s) + H2SO4(l) NaHSO4(s) + HCl(g)
Na2S(aq) + 2HCl(aq) H2S(g) + 2NaCl (s)
H2SO4(aq) + 2NaCN(aq) Na2SO4(aq) + 2HCN(g)
Double replacement reactions that form H2CO3, H2SO3
or NH4OH are quickly followed by the
decomposition of these compounds into gases
(indirect gas production).
Copyright 2012 John Wiley & Sons, Inc

38. Indirect Gas Forming Reactions
metal carbonate + acid  salt + CO2(g) + H2O(l)
Na2CO3(aq) + 2HCl(aq)  2NaCl(aq) + CO2(g) + H2O(l)
metal sulfite + acid  salt + SO2(g) + H2O(l)
Na2SO3(aq) + 2HCl(aq)  2NaCl(aq) + SO2(g) + H2O(l)
ammonium salt + base  salt + NH3(g) + H2O(l)
NH4NO3(aq) + NaOH(aq)  NaNO3(aq) + NH3(g) + H2O(l)
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39. Your Turn!
What are the likely products of the reaction of
copper(II) oxide with nitric acid?
a. CuNO3 + H2O
b. Cu(NO3)2 + H2O
c. Cu(NO2)2 + H2O
d. CuNO2 + H2O
CuO(s) + 2HNO3(aq) Cu(NO3)2(aq) + H2O(l)
Copyright 2012 John Wiley & Sons, Inc

40. Your Turn!
What are the likely products of the reaction of sodium
sulfide with iron(III) chloride?
a. FeS + NaCl
b. FeS3 + NaCl
c. Fe3S + NaCl
d. Fe2S3 + NaCl
2FeCl3(aq) + 3Na2S(aq) Fe2S3(s) + 6NaCl(aq)
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41. Your Turn!
What are the likely products of the reaction of sodium
hydrogen carbonate with hydrochloric acid?
a. NaCl + H2CO3
b. NaCl + H2O + CO2
c. NaCl + H2O + CO3
d. NaCl + H2 + CO3
NaHCO3(aq) + HCl(aq)  NaCl(aq) + H2O(l) + CO2(g)
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42. Heat in Chemical Reactions
Endothermic vs Exothermic
Endothermic reactions absorb heat
O2(g) + N2(g) + 181 kJ  2NO(g)
Exothermic reactions release heat
2 Al(s) + Fe2O3(s) 2Fe(s) + Al2O3(s) + 852 kJ
The amount of heat absorbed or released is the
heat of reaction.
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Review Question 4

43. Endothermic Reactions
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44. Exothermic Reactions
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45. Your Turn!
Consider the reaction: H2 + I2 + 12.6 kJ 2 HI. When
one mole of HI is produced
A. 12.6 kJ of energy is absorbed
B. 6.3 kJ of energy is absorbed
C. 12.6 kJ of energy is released
D. 6.3 kJ of energy is released
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46. Global Warming:
The Greenhouse Effect
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47. Global Warming:
The Greenhouse Effect
Increased carbon dioxide levels have caused a 0.74°C
rise in global temperatures over the last 100 years.
Copyright 2012 John Wiley & Sons, Inc

48. Questions
Review Questions
– Did in class
Paired Questions (pg 164)
– Do 1, 3, 7, 9, 11, 15, 21, 27, 29, 31, 35 , 39, 43
– Practice later 2, 6, 12, 16, 20, 24, 28, 32, 36, 40, 44
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