6
Some Types of Chemical
Reactions
Outline
1. Aqueous Solutions 水溶液: An Introduction
2. Reactions in Aqueous Solutions
Naming Some Inorganic Compounds
3. Naming Binary Compounds 二元化合物的命名
4. Naming Ternary Acids and Their Salts 三元酸的命名
Classifying Chemical Reactions
5. Oxidation-Reduction Reactions: An Introduction
6. Combination Reactions 化合反應
7. Decomposition Reactions 分解反應
8. Displacement Reactions分解反應
9. Metathesis Reactions 複分解反應
10. Gas-Formation Reactions
11. Summary of Reaction Types
2
Aqueous Solutions: An Introduction
Electrolytes and Extent of Ionization電解質及電解游離
程度
• Electrolytes are substances whose aqueous solutions conduct
electric current凡化合物溶於水能導電的物質即稱電解質
– Nonelectrolytes – solutes that do not conduct electricity in
water 非電解質
– Weak electrolytes: conduct electricity poorly in dilute
aqueous current 弱電解質:導電性較差
– Strong electrolytes: conduct electricity well in dilute
aqueous current 強電解質:導電性較好
• The strength of a electrolyte depends on the number of ions in
solution, and also on the charges on these ions 導電性的強度
取決於溶液的離子數目及離子的電荷
3
Nonelectrolytes
Weak electrolytes
strong electrolytes
4
Aqueous Solutions: An
Introduction
Nonelectrolytes – solutes that do not conduct
electricity in water
• C2H5OH - ethanol
• C6H12O6 – glucose 葡萄糖
(blood sugar)
• C12H22O11 – sucrose 蔗糖
(table sugar)
HO
H
H
H
C
HO
C
H2
C
CH
C
O
H
H
OH
C
C
H HO
H
C
OH
H
C
C
H
HO
HO
C
H
C
H
OH
O
O
H
HO
C
C
HO
H
H
H
OH
C
H2C
C
O
C
CH2
OH
5
Aqueous Solutions: An
Introduction
•The reason nonelectrolytes do not conduct
electricity is because they do not form ions in
solution.
• ions conduct electricity in solution
Acid: a substance that produces hydrogen ions, H+,
in aqueous solutions
Base: a substance that produces hydroxide ions, OH-,
in aqueous solutions
Salt: a compound that contains a cation other than
H+, and an anion other than hydroxide ion,
OH- , or oxide ion, O26
7
Aqueous Solutions: An
Introduction
•Classification of solutes
–strong electrolytes強電解質- conduct electricity extremely
well in dilute aqueous solutions
•Examples of strong electrolytes
1. HCl, HNO3, etc.
•strong soluble acids
2. NaOH, KOH, etc.
•strong soluble bases
3. NaCl, KBr, etc.
•soluble ionic salts
•ionize in water essentially 100%
檸檬酸
8
Aqueous Solutions: An
Introduction
•Classification of solutes
– weak electrolytes - conduct electricity
poorly in dilute aqueous solutions
1.CH3COOH, (COOH)2
•weak acids
2.NH3, Fe(OH)3
•weak bases
3.some soluble covalent salts
•ionize in water much less
than 100%
9
Aqueous Solutions: An
Introduction
Strong and Weak Acids 強酸及弱酸
•Acids are substances that generate H+ in aqueous
solutions.
•Strong acids ionize 100% in water.
HCl(g)
100%
H+(aq) + Cl-(aq)
HNO3 + H2O
HNO3
H2O
100%
H3O+(aq) + NO-3(aq)
H+(aq) + NO-3(aq)
10
Table 6-1
Aqueous Solutions: An
strong acids--ionize almost
Introduction 100%
氫氯酸
氫溴酸
氫碘酸
硝酸
過氯酸
氯酸
硫酸
11
Table 6-2
Aqueous Solutions: An
acids--Typically ionize
IntroductionWeak
10% or less!
氫氟酸
醋酸
氰化氫
亞硝酸
碳酸
亞硫酸
磷酸
草酸
12
Aqueous Solutions: An
Introduction
Organic acid 有機酸
•
•
•
•
Contain the carboxylate group, ―COOH
Most organic acids are weak
― COO- and H+
Naturally occurring organic weak acid
– Tartaric acid (grapes) 酒石酸
– Lactic acid (sour milk) 乳酸
– Formic acid (ants) 甲酸或稱蟻酸
Inorganic Acid 無機酸
• Often called mineral acids 礦物酸
• Contain Carbon but considered to be inorganic acid
– Carbonic acid, H2CO3 碳酸
– Hydrocyanic acid, HCN 氰化氫
13
Example 6-1 Strong and Weak Acid
In the following lists of common acids, which are
strong and which are weak?
(a) H3PO4, HCl, H2CO3, HNO3
(b) HClO4, H2SO4, HClO, HF.
(a) HCl, HNO3 are strong acids
H3PO4, H2CO3 are weak acids
(b) HClO4, H2SO4, are strong acids
HClO, HF are weak acids
Exercise 5, 7
14
Aqueous Solutions: An
Introduction
Reversible Reactions 可逆反應
• Strong acid : the ionization of HCl in water is nearly
complete
– one direction
• All weak inorganic acids ionize reversibly or in
equilibrium reactions.
– This is why they ionize less than 100%.
• Correct chemical symbolism for equilibrium reactions
CH3COOH (aq)
CH3COO-(aq) + H+(aq)
Reversible Reactions 可逆反應
15
Aqueous Solutions: An
Introduction
Strong Bases, Insoluble Bases, and Weak Bases 強鹼,
不可溶鹼及弱鹼
•Strong Bases 強鹼
–Characteristic of common inorganic bases is that they
produce OH- ions in solution.
–Similarly to strong acids, strong bases ionize 100% in water.
NaOH
Ba(OH)2
H2O
H2O
Na+(aq) + OH-(aq)
Ba+2(aq) + 2OH-(aq)
16
Aqueous Solutions: An
Introduction
Table 6-2
氫氧化鋰
氫氧化鈉
氫氧化鉀
氫氧化銣
氫氧化銫
氫氧化鈣
氫氧化鍶
氫氧化鋇
Notice that they are all hydroxides of IA and IIA metals
17
Aqueous Solutions: An
Introduction
Strong Bases, Insoluble Bases, and Weak Bases
• Insoluble bases
– Ionic compounds that are insoluble in water, consequently,
not very basic
– Cu(OH)2, Zn(OH)2, Fe(OH)2氫氧化亞鐵, Fe(OH)3
• Weak bases
– are covalent compounds that ionize slightly in water.
– Ammonia is most common weak base-- NH3
– Closely related N-containing compounds, the amines
• Methylamine CH3NH2甲胺
• Caffeine 咖啡因
NH3(aq) + H2O(l)
NH4+(aq) + OH-(aq)
18
Example 6-2 Classifying Bases
From the following lists, choose (i) the strong bases, (ii) the
insoluble bases, and (iii) the weak bases.
(a) NaOH, Cu(OH)2, Pb(OH)2, Ba(OH)2
(b) Fe(OH)3, KOH, Mg(OH)2, Sr(OH)2, NH3
(a) (i)The strong bases: NaOH, Ba(OH)2
(ii)The insoluble bases: Cu(OH)2, Pb(OH)2
(b) (i)The strong bases: KOH, Sr(OH)2
(ii)The insoluble bases: Fe(OH)3, Mg(OH)2
(iii)The weak bases: NH3
Exercise 8, 10
19
Aqueous Solutions: An
Introduction
Solubility 溶解度Guidelines for Compounds in Aqueous
Solutions
– It is very important that you know these guidelines and
how to apply them in reactions.
1) Common inorganic acids and low-molecular-weight
organic acids are water soluble
2) All common compounds of the Group IA metal ions
and the ammonium ion are water soluble.
– Li+, Na+, K+, Rb+, Cs+, and NH4+
20
Aqueous Solutions: An
Introduction
3) Common nitrates, acetates, chlorates, and
perchlorates are water soluble
– NO3-, CH3COO-, ClO3-, and ClO4硝酸根 醋酸根
氯酸根
過氯酸根
4) Common chlorides氯化物 are water soluble
– Exceptions – AgCl, Hg2Cl2, & PbCl2 (例外)
– Common bromides and iodides behave similarly to
chlorides.
– Common fluorides are water soluble.
•Exceptions – MgF2, CaF2, SrF2, BaF2, and PbF2
21
Aqueous Solutions: An
Introduction
5)Common sulfates are water soluble
–Exceptions – PbSO4, BaSO4, & HgSO4
–Moderately soluble – CaSO4, SrSO4, & Ag2SO4
6)Common metal hydroxides are water insoluble
–Exceptions – LiOH, NaOH, KOH, RbOH & CsOH (IA
metal hydroxides)
22
Aqueous Solutions: An
Introduction
7) Common carbonates, phosphates, and arsenates
are water insoluble
碳酸鹽,磷酸鹽及砷酸鹽
– CO32-, PO43-, & AsO43– Exceptions- IA metals and NH4+
Ba(CO3)2 is moderately soluble
– Moderately soluble – MgCO3
8) Common sulfides (S2-) are water insoluble
– Exceptions – IA metals and NH4+ plus IIA metals
23
Table 6-4
Aqueous Solutions: An
Introduction
Insoluble
soluble
24
Example 6-3 Solubility of Some Common Ionic Salt
From the following compounds, choose (a) those that are
likely to be soluble in water and (b) those that are likely to
be insoluble: NaBr, Cu(OH)2, PbCl2, AgI, Fe2O3, Mg(NO3)2,
(NH4)2SO4
(a)The soluble compound:
NaBr, Mg(NO3)2, (NH4)2SO4
(b)The insoluble compound:
Cu(OH)2, PbCl2, AgI, Fe2O3
Exercise 14, 16
25
Reactions in
Aqueous Solutions
There are three ways to write reactions in aqueous
solutions.
1. Molecular equation 分子方程式
– Show all reactants & products in molecular or ionic form
(more active metal replaces the compound)
Zn(s) + CuSO4(aq)
Cu(s) + 2AgNO3(aq)
ZnSO4(aq) +Cu(s)
Cu(NO3)2 (aq) + 2Ag(s)
Soluble ionic
compounds
26
Reactions in
Aqueous Solutions
There are three ways to write reactions in aqueous
solutions.
2.Total ionic equation 完全離子方程式
– Show the ions and molecules as they exist in solution
Zn(s) + Cu2+ (aq)+SO42-(aq)
Zn2+(aq) +SO42-(aq) +Cu(s)
2[Ag+ (s) +NO3- (aq)]+ Cu2+(aq)
1Ag(s) +[Cu2+(aq)+2NO3-(aq) ]
NO3- ions do not participate in the reaction
They do not change
 Spectator ions 旁觀離子
27
Reactions in
Aqueous Solutions
There are three ways to write reactions in aqueous
solutions.
3.Net ionic equation 淨離子方程式
– Shows ions that participate in reaction and removes
spectator ions旁觀離子
Zn(s) + Cu2+ (aq)+SO42-(aq)
Zn(s) + Cu2+(aq)
Zn2+(aq) +SO42-(aq) +Cu(s)
Zn2+(aq) +Cu(s)
2[Ag+ (s) +NO3- (aq)]+ Cu2+(aq)
2Ag+ (s) + Cu2+(aq)
2Ag(s) +[Cu2+(aq)+2NO3-(aq) ]
2Ag(s) +Cu2+(aq)
28
Reactions in
Aqueous Solutions
• In the total and net ionic equations the only common
substances that should be written as ions are:
a. Strong acids
b. Strong bases
c. Soluble ionic salts
29
Table 6-5
Reactions in
Aqueous Solutions
30
Naming Some Inorganic Compounds
無機化合物的命名
IUPAC 國際純粹與應用化學聯合會
• Binary compounds (二元化合物) are made of two
elements.
–metal + nonmetal = ionic compound (離子化合物)
–nonmetal + nonmetal = covalent compound
(共價化合物 )
• Name the more metallic element first.
– Use the element’s name.
• Name the less metallic element second.
– Add the suffix “ide” to the element’s stem.
(字尾加上ide )
31
Table 6-6
陽離子
陰離子
32
33
Naming Some
Inorganic Compounds
•Nonmetal Stems
Element
Boron (B)
Carbon (C)
Silicon (Si)
Nitrogen (N)
Phosphorus (P)
Arsenic (As)
Antimony (Sb)
Stem
bor
carb
silic
nitr
phosph
arsen
antimon
Element
Oxygen (O)
Sulfur (S)
Selenium (Se)
Tellurium (Te)
Hydrogen (H)
Fluorine (F)
Chlorine (Cl)
Bromine (Br)
Iodine (I)
Stem
ox
sulf
selen
tellur
hydr
fluor
chlor
brom
iod
34
Naming Some
Inorganic Compounds
•Binary Ionic Compounds are made of a metal cation
and a nonmetal anion.
– Cation named first
– Anion named second
LiBr
lithium bromide
MgCl2
magnesium chloride
Li2S
lithium sulfide
Al2O3
aluminum oxide
Na3P
sodium phosphide
Mg3N2
magnesium nitride
Notice that binary ionic compounds with metals having one
oxidation state (representative metals) do not use prefixes
or Roman numerals.
35
Naming Some
Inorganic Compounds
• Binary ionic compounds containing metals that
exhibit more than one oxidation state
• Metals exhibiting multiple oxidation states are:
1. most of the transition metals
2. metals in groups 3A (except Al), 4A, & 5A
36
Naming Some
Inorganic Compounds
• There are two methods to name these compounds.
1. Older method
– add suffix “ic” to element’s Latin name for higher
oxidation state
– add suffix “ous” to element’s Latin name for lower
oxidation state
2. Modern method
– use Roman numerals in parentheses to indicate
metal’s oxidation state
37
Naming Some
Inorganic Compounds
Compound
FeBr2 +2
FeBr3 +3
SnO +2
SnO2 +4
TiCl2 +2
TiCl3 +3
TiCl4 +4
Old System
ferrous bromide
ferric bromide
stannous oxide
stannic oxide
titanous chloride
Titanic chloride
does not work
Modern System
Iron (II) bromide
Iron (III) bromide
Tin (II) oxide
Tin (IV) oxide
Titanium (II) chloride
Titanium (III) chloride
Titanium (IV) chloride
38
Naming Some
Inorganic Compounds
Pseudobinary ionic compounds
• There are three polyatomic ions that commonly form
binary ionic compounds.
1.OH- hydroxide
2.CN- cyanide
3.NH4+ ammonium
Pseudo = false 假的
39
Naming Some
Inorganic Compounds
Use binary ionic compound naming system.
KOH
Ba(OH)2
Al(OH)3
Fe(OH)2
Fe(OH)3
Ba(CN)2
(NH4)2S
NH4CN
Cu(OH)2
potassium hydroxide
barium hydroxide
aluminum hydroxide
iron (II) hydroxide
iron (III) hydroxide
barium cyanide
ammonium sulfide
ammonium cyanide
copper (II) hydroxide
40
Naming Some
Inorganic Compounds
• Binary acids are binary compounds consisting of
hydrogen and a nonmetal.
• Compounds are usually gases at room temperature and
pressure.
– Nomenclature for the gaseous compounds is hydrogen
(stem)ide.
• When the compounds are dissolved in water they form
acidic solutions.
– Nomenclature for the acidic solutions is hydro (stem)ic acid.
Formula
HCl
HF
H2S
HCN
Name of compound
hydrogen chloride
hydrogen fluoride
hydrogen sulfide
hydrogen cyanide
Name of Aqueous solution
hydrochloric acid, HCl(aq)
hydrofluoric acid, HF(aq)
hydrosulfuric acid, H2S(aq)
Hydrocyanic acid, HCN(aq)
41
Naming Some
Inorganic Compounds
• Binary covalent molecular compounds composed of two
nonmetals other than hydrogen
– Nomenclature must include prefixes that specify the
number of atoms of each element in the compound.
• Use the minimum number of prefixes necessary to
specify the compound.
– Frequently drop the prefix mono- 1
2 di
5 penta
8 oct
3 tri
6 hexa
9 nona
4 tetra
7 hepta
10 deca
42
Naming Some
Inorganic Compounds
Formula
CO
CO2
SO3
OF2
P4O6
P4O10
Name
carbon monoxide
carbon dioxide
sulfur trioxide
oxygen difluoride
tetraphosphorus hexoxide
tetraphosphorus decoxide
43
Naming Some
Inorganic Compounds
•The oxides of nitrogen illustrate why covalent compounds
need prefixes and ionic compounds do not.
•Formula
Old Name
Modern Name
•N2O
nitrous oxide
dinitrogen monoxide
•NO
nitric oxide
nitrogen monoxide
•N2O3
nitrogen trioxide
dinitrogen trioxide
•NO2
nitrogen dioxide
nitrogen dioxide
•N2O4
nitrogen tetroxide dinitrogen tetroxide
•N2O5
nitrogen pentoxide dinitrogen pentoxide
44
Naming Some
Inorganic Compounds
• Ternary Acids and Their Salts are made of three
elements.
– The elements are H, O, & a nonmetal.
• Two of the compounds are chosen as the basis for
the nomenclature system.
– Higher oxidation state for nonmetal is named (stem)ic
acid.
– Lower oxidation state for nonmetal is named (stem)ous
acid
• Salts are named based on the acids.
– Anions of -ic acids make “ate” salts.
– Anions of -ous acids make “ite” salts.
45
Table 6-7
Naming Some
Inorganic Compounds
46
Naming Some
Inorganic Compounds
• Salts are formed by the reaction of the acid with a
strong base.
Acid
HNO2
nitrous acid
HNO3
nitric acid
H2SO3
sulfurous acid
H2SO4
sulfuric acid
HClO2
chlorous acid
HClO3
chloric acid
Salt
NaNO2
sodium nitrite
NaNO3
sodium nitrate
Na2SO3
sodium sulfite
Na2SO4
sodium sulfate
NaClO2
sodium chlorite
NaClO3
sodium chlorate
47
Naming Some
Inorganic Compounds
• There are two other possible acid and salt
combinations.
• Acids that have a higher oxidation state than the “ic”
acid are given the prefix “per”.
– These acids and salts will have one more O atom than the
“ic” acid.
• Acids that have a lower oxidation state than the
“ous” acid are given the prefix “hypo”.
– These acids and salts will have one less O atom than the
“ous” acid.
48
Naming Some
Inorganic Compounds
• Illustrate this series of acids and salts with the Cl
ternary acids and salts.
Acid
Na Salt
HClO
NaClO
hypochlorous acid
sodium hypochlorite
HClO2
NaClO2
HClO3
NaClO3
HClO4
NaClO4
chlorous acid
chloric acid
perchloric acid
sodium chlorite
sodium chlorate
sodium perchlorate
49
Naming Some
Inorganic Compounds
• Acidic Salts are made from ternary acids that retain
one or more of their acidic hydrogen atoms.
– Made from acid base reactions where there is an
insufficient amount of base to react with all of the
hydrogen atoms.
• Old system used the prefix “bi” to denote the
hydrogen atom.
• Modern system uses prefixes and the word
hydrogen.
50
Naming Some
Inorganic Compounds
• NaHCO3
Old system
Modern system
• KHSO4
Old system
Modern system
• KH2PO4
Old system
Modern system
• K2HPO4
Old system
Modern system
sodium bicarbonate
sodium hydrogen carbonate
potassium bisulfate
potassium hydrogen sulfate
potassium bis biphosphate
potassium dihydrogen phosphate
potassium biphosphate
potassium hydrogen phosphate
51
Naming Some
Inorganic Compounds
• Basic Salts are analogous to acidic salts.
– The salts have one or more basic hydroxides remaining in
the compound.
• Basic salts are formed by acid-base reactions with
insufficient amounts of the acid to react with all of
the hydroxide ions.
• Use prefixes to indicate the number of hydroxide
groups.
52
Naming Some
Inorganic Compounds
• Ca(OH)Cl
– calcium monohydroxy chloride
• Al(OH)Cl2
– aluminum monohydroxy chloride
• Al(OH)2Cl
– aluminum dihydroxy chloride
53
Oxidation-Reduction Reactions:
An Introduction
•Oxidation is an increase in the oxidation number. (氧化數增加)
– Corresponds to the loss of electrons. 失去電子
•Reduction is a decrease in the oxidation number. (氧化數減少)
– Good mnemonic – reduction reduces the oxidation number.
– Corresponds to the gain of electrons 得到電子
54
Oxidation-Reduction Reactions:
An Introduction
•Oxidizing agents氧化劑are chemical species that:
1.oxidize some other substance
2.contain atoms that are reduced in the reaction
3.gain electrons
•Reducing agents還原劑are chemical species that:
1.reduce some other substance
2.contain atoms that are oxidized in the reaction
3.lose electrons
55
Oxidation-Reduction Reactions:
An Introduction
• Two examples of oxidation-reduction or redox
reactions.
• KMnO4 and Fe2+
– Fe2+ is oxidized to Fe3+
– MnO41- is reduced to Mn2+
• Combustion reactions are
redox reactions
• Combustion of Mg
– Mg is oxidized to MgO
– O2 is reduced to O2-
56
Oxidation-Reduction Reactions:
An Introduction
0
0
+3 -1
2Fe(s) + 3Cl2(g)
Reducing agent
2FeCl3(s)
Oxidizing agent
+3 -1
0
2FeBr3(aq) + 3Cl2(g)
Reducing agent
+3 -1
0
2FeCl3(s) + 3Br2(l)
Oxidizing agent
Disproportionation Reaction 不均化反應 is a redox reaction
in which the same element is oxidized and reduced.
0
-1
+1
Cl2 + H2O
HCl + HClO
Reducing agent
Oxidizing agent
57
Oxidation-Reduction Reactions:
An Introduction
• Example 4-2: Write and balance the formula unit, total ionic, and
net ionic equations for the oxidation of sulfurous acid to sulfuric
acid by oxygen in acidic aqueous solution.
• Formula unit equation
2H2SO3 (aq) + O2(g)
2H2SO4 (aq)
• Total ionic equation
2H2SO3 (aq) + O2(g)
+4
0
2H2SO3 (aq) + O2(g)
Reducing agent
4H+ (aq)+ 2SO42- (aq)
+6 -2
4H+ (aq)+ 2SO42- (aq)
Oxidizing agent
58
Example 6-4 Redox Reactions
Write each of the following formula unit equations as a net ionic equation
if the two differ. Which ones are redox reactions? For the redox reactions,
identify the oxidizing agent, the reducing agent, the species oxidized, and
the species reduced?
(a) 2AgNO3 (aq) + Cu(s)
Cu(NO3)2(aq)+ 2Ag (s)
(b) 4KClO3 (s)
KCl(s)+ 3KClO4(s)
(c) 3AgNO3 (aq) + K3PO4(aq)
Ag3 PO4(s)+ 3KNO3(aq)
(a)
+1
2[Ag+
+5 -2
(aq)+NO3 (aq)]
Oxidizing agent
(b) 4KClO3 (s)
(c)
3Ag+
+2
[Cu+2
+ Cu(s)
+5 -2
-
(aq) +2NO3 (aq)]+
0
2Ag (s)
Reducing agent
+1 +5 -2
+1
0
+5 -2
+1 -1
+1 +7 -2
KCl(s)+ 3KClO4(s)
3(aq)+PO4 (aq)
Disproportionation
Reaction
+1 +5 -2
Ag3 PO4(s)
Not a Redox Reaction
Exercise 56, 59
59
Combination Reactions
化合反應
• Combination reactions occur when two or more
substances combine to form a compound.
• There are three basic types of combination
reactions.
1. Two elements react to form a new compound
2. An element and a compound react to form one
new compound
3. Two compounds react to form one compound
60
Combination Reactions
1.Element + Element  Compound
(oxidation-reduction reaction)
A. Metal + Nonmetal  Binary Ionic Compound
2M (s) + X2(g)
2(M+X-) (s) M: Li, Na, K, Rb, Cs
2Na (s) + Cl2(g)
M (s) + X2(g)
Mg (s) + F2(g)
2NaCl (s)
MX2(s)
X: F, Cl, Br, I
Sodium Chloride
M: Be, Mg, Ca, Sr, Ba
X: F, Cl, Br, I
MgF2(s)
Magnesium Fluoride
61
Combination Reactions
1. Element + Element  Compound
B. Nonmetal + Nonmetal  Covalent Binary Compound
P4 (s) + 5O2(g)
P4O10(s)
P4 (s) + 6Cl2(g)
4PCl3(l)
62
Combination Reactions
1.Element + Element  Compound
B. Nonmetal + Nonmetal  Covalent Binary Compound
• Can control which product is made with the reaction conditions.
2As (s) + 3Cl2(g)
2AsCl3(s)
In limited chlorine
2As (s) + 5Cl2(g)
2AsCl5(s)
In excess chlorine
A higher oxidation state of a nonmetal is formed when it
reacts with an excess of another nonmetal
Se (s) + 2F2(g)
Se (s) + 3F2(g)
SeF4(s)
SeF6(s)
In limited fluorine
In excess fluorine
63
Combination Reactions
2. Compound + Element  Compound
(oxidation-reduction reaction)
AsCl3 (s) + 2Cl2(g)
PCl3 (l) + Cl2(g)
SF4 (g) + F2(g)
AsCl5(s)
PCl5(s)
SF6(g)
The reaction of oxygen with oxides of nonmetals is an example of this
type of combination reaction.
2CO (g) + O2(g)
2CO2(g)

2SO2 (g) + O2(g) catalyst
2SO3(g)
P4O6 (g) + 2O2(g)
P4O10(g)
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Combination Reactions
3. Compound + Compound  Compound
– Calcium oxide with carbon dioxide to produce calcium carbonate
CaO (s) + CO2(g)
CaCO3(s)
– Pyrosulfuric acid is produced by dissolving sulfur trioxide in
concentrated sulfuric acid
SO3 (g) + H2SO4(l)
H2S2O7(l)
– Pyrosulfuric acid is then diluted with water to make H2SO4
H2S2O7 (l) + H2O(l)
2H2SO4(l)
– Oxides of the Group 1A and 2A metals react with water to form
metal hydroxides
CaO (s) + H2O(l)
Ca(OH)2(aq)
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Decomposition Reactions
分解反應
•Decomposition reactions occur when one compound
decomposes to form:
1. Two elements
2. One or more elements and one or more compounds
3. Two or more compounds
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Decomposition Reactions
1. Compound  Element + Element
• decomposition of dinitrogen oxide
2N2O(g)

2N2(g) + O2(g)
• decomposition of calcium chloride
CaCl2(l)
electricity
Ca(l) + Cl2(g)
• decomposition of silver halides
2AgBr(s)
h
2Ag(s) + Br2(g)
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Decomposition Reactions
2. Compound  One Element + Compound(s)
– The alkali metal chlorites, such as KClO3, decompose when
heated to produce the corresponding chlorides and liberate
oxygen
2KClO3 (s)

MnO2
Potassium chlorate
2KCl(s) + 3O2(g)
Potassium chloride
– Nitrate salts of alkali metals or alkaline earth metals
decompose to form metal nitrite and oxygen
2NaNO3 (s)
2NaNO2(s) + O2(g)
– Hydrogen peroxide decompose to form water and oxygen
2H2O2 (l)
2H2O(l) + O2(g)
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Decomposition Reactions
3. Compound  Compound + Compound
– decomposition of calcium carbonate produced a metal oxide
and carbon dioxide
CaCO3 (s)

2Mg(OH)2 (s)

CaO(s) + CO2(g)
– Solid hydroxides decompose to form a metal oxide and water
vapor
MgO(s) + H2O (g)
– Ammonium salts lose ammonia
(NH4) 2SO4 (s)

2NH3 (g) + H2SO4(l)
– Ammonium salt contains an anion that is strong oxidizing
agent, its decomposition reaction produces an oxide, water
and nitrogen gas.
(NH4) 2Cr2O7 (s)

Cr2O3 (s) + 4H2O (g) + N2 (g)
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Displacement Reactions
置換反應
• Displacement reactions occur when one element displaces
another element from a compound.
– These are redox reactions in which the more active metal
displaces the less active metal of hydrogen from a
compound in aqueous solution.
– Activity series is given in Table 4-14.
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Displacement Reactions
1. [More Active Metal + Salt of Less Active Metal]  [Less
Active Metal + Salt of More Active Metal]
–molecular equation
AgNO3 (aq) + Cu(s)
Ag (s)+ CuNO3 (aq)
• Total ionic equation
Ag+ (aq) +NO32-(aq) +Cu(s)
Cu+(aq)+ NO3-(aq) +Ag(s)
• Net ionic equation
Ag+ (aq)+Cu(s)
Cu+(aq)+ Ag(s)
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Displacement Reactions
2. [Active Metal + Nonoxidizing Acid]  [Hydrogen + Salt of Acid]
– Common method for preparing hydrogen in the laboratory.
– HNO3 is an oxidizing acid.
 Molecular equation
3H2SO4 (aq)+ 2Al(s)
•Total ionic equation
3H2(g)+ Al2 (SO4)3 (aq)
6H+ (aq)+3SO42-(aq) +2Al(s)
2Al3+(aq)+3SO42-(aq) +3H2(g)
•Net ionic equation
6H+ (aq)+2Al(s)
2Al3+(aq)+3H2(g)
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Displacement Reactions
•The following metals are active enough to displace
hydrogen
–K, Ca, Na, Mg, Al, Zn, Fe, Sn, & Pb
•Notice how the reaction changes with an oxidizing
acid.
–Reaction of Cu with HNO3.
• H2 is no longer produced.
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Displacement Reactions
3. [Active Nonmetal + Salt of Less Active Nonmetal] 
[Less Active Nonmetal + Salt of More Active Nonmetal]
• Molecular equation
Cl2(g)+2NaI(aq)
I2(s)+2NaCl(aq)
•Total ionic equation
Cl2 (g) +2Na+(aq)+ 2I-(aq)
2Na+(aq)+2Cl-(aq) + I2(s)
• Net ionic equation
Cl2 (g) +2I-(aq)
2Cl-(aq) + I2(s)
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Metathesis Reactions
複分解反應
• Metathesis reactions occur when two ionic aqueous
solutions are mixed and the ions switch partners.
AX + BY  AY + BX
• Metathesis reactions remove ions from solution in two
ways:
1. form predominantly unionized molecules like H2O
2. form an insoluble solid
• Ion removal is the driving force of metathesis reactions.
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Metathesis Reactions
1. Acid-Base (neutralization) Reactions
– Formation of the nonelectrolyte H2O
– acid + base  salt + water
• Molecular equation
HBr (aq)+ KOH(aq)
KBr(aq)+ H2O(l)
• Total ionic equation
H+(g) +Br-(aq)+ K+(aq)+OH-(aq)
K+(aq)+ Br-(aq) + H2O(l)
• Net ionic equation
H+(aq) +OH-(aq)
H2O(l)
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Metathesis Reactions
• Molecular equation
Ca(OH)2(aq)+2HNO3(aq)
Ca(NO3) 2(aq)+ 2H2O(l)
• Total ionic equation
Ca2+(aq) +2OH-(aq)+ 2H+(aq)+2NO3-(aq)
Ca2+(aq)+2NO-3(aq) +2 H2O(l)
• Net ionic equation
H+(aq) +OH-(aq)
H2O(l)
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Metathesis Reactions
2. Precipitation reactions沉澱 are metathesis
reactions in which an insoluble compound is
formed.
– The solid precipitates out of the solution much like rain
or snow precipitates out of the air.
• Molecular equation
Ca(NO3)2 (aq)+K2CO3 (aq)
2KNO3(aq)+ 2CaCO3(s)
• Total ionic equation
Ca2+(aq)+2NO3- (aq)+ 2K+(aq)+CO32-(aq)
2K+(aq)+2NO-3(aq) +CaCO3(s)
• Net ionic equation
Ca2+(aq) +CO32-(aq)
CaCO3(s)
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Metathesis Reactions
• Molecular equation
3CaCl2 (aq)+2Na2PO4 (aq)
6NaCl(aq)+ Ca3 (PO4)2(s)
• Total ionic equation
3Ca2+(aq)+6Cl- (aq)+ 6Na+(aq)+2PO43-(aq)
6Na+(aq)+6Cl-(aq) +Ca3 (PO4)2(s)
• Net ionic equation
3Ca2+(aq) +2PO43-(aq)
Ca3 (PO4)2(s)
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Metathesis Reactions
• Molecular equation
2HCl (aq)+Na2SO3 (aq)
2NaCl(aq)+ H2O(l)+SO2(g)
• Total ionic equation
2H+(aq)+2Cl- (aq)+ 2Na+(aq)+SO32-(aq)
2Na+(aq)+2Cl-(aq)+ H2O(l)+SO2(g)
• Net ionic equation
2H+(aq) +SO32-(aq)
H2O(l)+SO2(g)
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Gas-Formation Reactions
• A gas-formation reaction is a type of reaction in which there
is a formation of an insoluble or slightly soluble gas when
there are no gaseous reactants.
• Displacement reactions in which an active metal displaces
from an acid or from water are gas-formation reactons; they
are not methathesis reactions.
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Gas-Formation Reactions
• Consider hydrochloric acid with calcium carbonate to form
carbonic acid.
Formula Unit
2HCl(aq)+CaCO3 (s) H2CO3 (aq)+CaCl2 (aq)
Total Ionic
2[H+(aq)+Cl-(aq)] + CaCO3 (s)  H2CO3 (aq) +[Ca2+(aq) +2Cl-(aq)]
Net Ionic
2H+(aq) + CaCO3 (s)  H2CO3 (aq) + Ca2+(aq)
• Enough heat is generated in the reaction to cause thermal
decomposition of carbonic acid.
H2CO3 (aq)  CO2(g) + H2O(l)
• The net effect of the chemical reaction and subsequent
decomposition is
2HCl(aq) + CaCO3 (s)  CO2(g) + H2O(l) + CaCl2 (aq)
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84
85
Example 6-14 Classifying Reactions
Classifying each of the following reactions.
(a) Zn(s) + 2AgNO3 (aq)
Zn(NO3)2(aq)+ 2Ag (s)
(b) Ca(OH)2 (s)
CaO(s)+ H2O(l)
(c) 2HI (g)
H2(g)+ I2(g)
(d) Cu(NO3)2 (aq)+Na2S(aq)
NaNO3(aq)+CuS(s)
(e) SO2 (g)+H2O(l)
H2SO3 (aq)
(f) H2SO3 (aq)+2KOH(aq)
K2SO3 (aq)+ 2H2O(l)
(a) Zn displace Ag displacement reaction
Zn is oxidized and Ag is reduced Redox reaction
(b) A simple compound breaks into two compounds
decomposition reaction
(c) A simple compound breaks into two elements
decomposition reaction alsoRedox reaction
(d) Two reactant compounds change partners
metathesis reaction
Insoluble CuS  precipitation reaction
(e) Two compounds combine to form a single product
combination reaction
(f) Change partners metathesis reaction
acid-base react to form a salt and water
acid-base (neutralization) reaction
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Exercise 117-127