Types of Reactions
Chapter 8
Chemical
Reactions
•
There are six types of chemical
reactions that you will learn about in
this lesson:
1.
2.
3.
Types of Chemical
Reactions
4.
5.
6.
•
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Synthesis reactions
Decomposition reactions
Single displacement reactions
Double displacement reactions
Combustion reactions
Acid/Base reactions
At the end of the lesson, you should
be able to identify the type of
reaction and predict the product(s)
product(s)
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Synthesis Reactions
Synthesis Reactions
Synthesis reactions occur when two substances (generally
elements)
elements) combine and form a compound.
compound. (Sometimes
these are called combination or addition reactions.)
Synthesis reactions occur when two substances (generally
elements)
elements) combine and form a compound.
compound.
reactant + reactant Æ 1 product
Or, basically: A + B Æ AB
Example:
Example:
2H2 + O2 Æ 2H2O
C + O2 Æ CO2
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Skeleton Equation:
Na + Cl2 Æ NaCl
Balanced Equation:
2Na + Cl2 Æ 2NaCl
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Synthesis Reactions
Another example of a synthesis reaction …
Chlorine gas reacts with oxygen to form
dichlorine pentoxide:
pentoxide:
Skeleton Equation:
Cl2 + O2 Æ Cl2O5
Balanced Equation:
2Cl2 + 5O2 Æ 2Cl2O5
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Sodium metal reacts with chlorine gas to form sodium
chloride:
Decomposition Reactions
Decomposition reactions occur when a compound
breaks up into the elements or to a few
simpler compounds
1 Reactant Æ Product + Product
In general: AB Æ A + B
Examples: 2 H2O Æ 2H2 + O2
2 HgO Æ 2Hg + O2
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Decomposition Reactions
Single Replacement Reactions
Decomposition: a compound breaks up
Single Replacement Reactions occur when one
element replaces another in a compound.
A practical example of decomposition: an
automobile airbag
A + X Y Æ AY + X
Sodium nitride breaks down to sodium metal and
nitrogen gas:
Skeleton Equation:
Na3N Æ Na +
Balanced Equation:
2Na3N Æ 6Na + N2
N2
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Single Replacement Reactions
Single Replacement Reactions
Metal Replaces Metal
There are generally two types of single
replacement reactions
•
Keep in mind …
•
•
Na F
Zinc reacts with Hydrochloric Acid to form Zinc
chloride and hydrogen gas
Skeleton Equation:
Zn(s)
(s) + HCl(aq)
(aq) Æ ZnCl2(s) + H2(g)
cationic metal
anionic nonmetal
Cationic: A metal can replace a metal
A + BC Æ AC + B (A & B are metals)
The Balanced Equation …
Zn(s)
(s) + 2 HCl(aq)
(aq) Æ ZnCl2(s) + H2(g)
Anionic: A nonmetal can replace a nonmetal
D + EF
EF Æ ED + F (D & F are nonmetals)
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Single Replacement Reactions
Single Replacement Reactions
An Investigation; The Aluminum Soda Can
An Investigation; The Aluminum Soda Can
•
•
•
Are they all made of the same amount of
Aluminum?
Aluminum?
Do they have the same wall thickness?
Would you expect Coca Cola cans to be
different than Dr. Pepper?
Let’
Let’s try to “Rip”
Rip” one of each can …
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•
Aluminum metal reacts with aqueous copper (II)
chloride
Al(s)
---> AlCl3(aq) + Cu(s)
(s) + CuCl2(aq) --->
(s) (Skeleton)
Is it Balanced???
2Al(s) + 3CuCl2(aq) --->
---> 2AlCl3(aq) + 3Cu(s)
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Single Replacement Reactions
Single Replacement Reactions
Let’s Revisit the Soda Can Reaction.
Could We have predicted the Products?
How Do We Know
if one Metal
Replaces
Another?
Al(s)
(s) + CuCl2(aq) Æ ?
Which is more reactive, Al of Cu?
Al(s)
(s) + CuCl2(aq) Æ AlCl3(aq) + Cu(s)
(s)
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GHS Honors Chem
Single Replacement Reactions
Single Replacement Reactions
Predicting Single Replacement of Metals
What About Nonmetal Replacing Nonmetal?
• Iron reacts with aqueous copper (II) chloride
Fe(s)
(s) + CuCl2(aq) Æ ?
Is Iron More Active than Copper on the Activity Chart?
Fe(s)
(s) + CuCl2(aq) Æ FeCl2(aq) + Cu(s)
(s)
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Fluorine reacts with Hydrochloric Acid to form
Chlorine and Hydrogen fluoride
Skeleton Equation:
F2(g) + HCl(aq)
(aq) Æ HF(aq)
(aq) + Cl2(g)
The Balanced Equation …
F2(g) + 2 HCl(aq)
(aq) Æ 2 HF(s)
(s) + Cl2(g)
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Single Replacement Reactions
Single Replacement Reactions
Predicting Single Replacement of Nonmetals
How Do We Know
if one Nonmetal
Replaces
Another?
More Active
• Cl2 + HBr Æ
?
• I2
+ HCl Æ
?
• F2
+
?
HI
Æ
Less Active
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Double Replacement Reactions
Double Replacement Reactions
•
Double Replacement Reactions occur when a
metal replaces a metal in a compound and a
nonmetal replaces a nonmetal in a compound
•
•
AB + CD Æ AD + CB
Think about it like “foil”
foil”ing in algebra, first
and last ions go together + inside ions go
together
Example:
AgNO
AgNO3(aq) + NaCl
NaCl(aq)
(aq) Æ AgCl(s)
(s) + NaNO3(aq)
Another example:
K2SO4(aq) + Ba(NO
Ba(NO3)2(aq) Æ 2 KNO3(aq) + BaSO4(s)
•
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Combustion Reactions
Combustion Reactions occur when a substance
combines with oxygen releasing a large amount of
energy in the form of light and heat,
heat, it is a
combustion reaction.
Combustion Reactions
Combustion Reactions; substance combines with oxygen
releasing a large amount of energy in the form of light and
heat,
heat, as well as CO2 and H2O.
Let’
Let’s try to balance a few Combustion Reactions …
i.e Combustion of Propane, C3H8
1.
C3H8 + 5 O2 Æ 3 CO2 + 4 H2O + heat
2. 2 C2H6 + 7 O2 --->
---> 4 CO2 + 6 H2O
In addition to light and heat, CO2 and H2O are
always released during Complete Combustion
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3.
C6H12O6 +6 O2 --->
---> 6 CO2 + 6 H2O
4.
C2H6O + 3 O2 --->
---> 2 CO2 + 3 H2O
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Acid/Base Reactions
According to Bronsted Lowery:
An acid is any compound which can donate
„
a proton.
proton.
A base is any compound which can accept a
„
proton.
proton.
In an acid„
acid-base reaction,
reaction, an acid and a base
will react to form a salt and water. During the
reaction, a proton is donated by the acid to
the base to yield water. The remaining ions
form a salt.
CH4 + 2 O2 --->
---> CO2 + 2 H2O
Acid/Base Reactions
More examples:
H2SO4 + H2O Æ HSO4- + H3O+
„
„
HF + NaOH Æ NaF + HOH
„
HCN + CH3COO- Æ CN- + CH3COOH
HCl + NaOH Æ NaCl + H2O
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Let’
Let’s Summarize …
1. Synthesis reactions: two substances combine to form a
compound.
i.e. 2H2 + O2 Æ 2H2O
2. Decomposition reactions occur when a compound breaks
up.
i.e. 2 H2O Æ 2H2 + O2
3. Single Replacement reactions occur when one element
replaces another in a compound.
i.e. Zn(s)
(s) + 2 HCl(g)
(g) Æ ZnCl2(s) + H2(g)
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Let’
Let’s Summarize …
4. Double Displacement reactions: when a metal replaces a
metal in a compound and a nonmetal replaces a nonmetal in
a compound
(s)) Æ AgCl(s
i.e. AgNO
NaCl(s
AgCl(s)) + NaNO3(aq)
AgNO3(aq) + NaCl
5. Combustion reactions when a substance combines with
oxygen releasing a large amount of energy in the form of
light and heat,
heat, as well as CO2 and H2O.
i.e. C3H8 + 5 O2 Æ 3 CO2 + 4 H2O + heat
6. Acid/Base Reactions::
Reactions:: Acids donate a proton (H+) to a
base, producing a salt and water.
i.e.
HCl + NaOH Æ NaCl + H2O
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