1. Chapter 8 Chemical Reactions
8.3 Types of Reactions
Learning Goal Identify a reaction as a combination, decomposition, single replacement, double replacement, or combustion.
In a combination reaction, two or more substances combine to form one substance as the product.
© 2014 Pearson Education, Inc.

2. Types of Reactions
Chemical reactions may be classified as
combination
decomposition
single replacement
double replacement
combustion

3. Combination Reactions
In a combination reaction,
two or more elements form one product
two or more simple compounds combine to form one product
2Mg(s) + O2(g)  2MgO(s)
N2(g) + 3H2(g)  NH3 (g)

4. Combination Reactions
In a combination reaction, two or more substances combine to form one substance as the product.

5. Decomposition Reactions
In a decomposition reaction,
one reactant splits into two or more simpler substances

6. Decomposition Reactions
In a decomposition reaction, one reactant breaks down into two or more products.

7. Chemistry Link to Health
Photochemical smog
is prevalent in cities that depend on cars for transportation
is formed when nitrogen oxide (NO) emissions from cars combine with oxygen gas to form nitrogen dioxide
2NO(g) + O2(g)  2NO2(g)

8. Chemistry Link to Health
Nitrogen dioxide (NO2) gas
is a reddish-brown gas that irritates eyes and is damaging to lungs
reacts in the presence of sunlight to form NO molecules and O atoms
NO2(g)  NO(g) + O(g)
oxygen atoms

9. Chemistry Link to Health
The reddish-brown color of smog is due to nitrogen dioxide.

10. Chemistry Link to Health
Single oxygen atoms are very reactive and combine with molecules in the atmosphere to form ozone.
O(g) + O2(g)  O3(g) Ozone
In the lower atmosphere, ozone
irritates the eyes and respiratory tract
damages fabric and rubber as well as trees and crops

11. Single-Replacement Reactions
In a single-replacement reaction, an uncombined element replaces an element in a compound.
Zn(s) + 2HCl(aq)  ZnCl2(aq) + H2(g)
Fe(s) + CuSO4(aq)  FeSO4(aq) + Cu(s)

12. Single-Replacement Reactions
In a single replacement reaction, an atom or ion replaces an atom or ion in a compound.

13. Double-Replacement Reactions
In a double-replacement reaction, two elements in the reactants exchange places.
AgNO3(aq) + NaCl(aq)  AgCl(s) + NaNO3(aq)
NaOH(aq) + HCl(aq)  NaCl(aq) + HOH(l)

14. Double-Replacement Reactions
In a double replacement reaction, the positive ions in the reactants replace each other.

15. Combustion Reactions
In a combustion reaction, carbon containing compounds, fuel burns in oxygen from the air to produce carbon dioxide, CO2, water, H2O, and heat or flame.

16. Combustion Reactions
Butane, an alkane with 4 C atoms and 10 H atoms, is used as a fuel for a camp stove.

17. Summary of Reaction Types

18. Learning Check
Identify each type of reaction as
(C) combination (D) decomposition
(SR) single replacement
(DR) double replacement
3Ba(s) + N2(g)  Ba3N2(s)
2Ag(s) + H2S(aq)  Ag2S(s) + H2(g)
SiO2(s) + 4HF(aq)  SiF4(s) + 2H2O(l)
K2CO3(s)  K2O(aq) + CO2(g)

19. Solution
Identify each type of reaction as
(C) combination (D) decomposition
(SR) single replacement
(DR) double replacement
C 3Ba(s) + N2(g)  Ba3N2(s)
SR 2Ag(s) + H2S(aq)  Ag2S(s) + H2(g)
DR SiO2(s) + 4HF(aq)  SiF4(s) + 2H2O(l)
D K2CO3(s)  K2O(aq) + CO2(g)