1. Ch. 8 Chemical Equations and Reactions
8.2a Types of Chemical Reactions

2. Types of Chemical Reactions
5 basic types discussed here
not all reactions fall in these categories
you should be able to:
categorize a reaction by its reactant(s)
predict the product(s)

3. 1. Synthesis also called composition reaction reactants:
more than one
can be elements or compounds
products: only one compound
A + X  AX
where A is the cation and X is anion

4. 1. Synthesis Rubidium and sulfur Rb(s) + S8(s)  Rb2S(s)
Magnesium and oxygen
Mg(s) + O2(g)  MgO(s)
Sodium and chlorine
Na(s) + Cl2(g)  NaCl(s)
Magnesium and fluorine
Mg(s) + F2(g)  MgF2(s)

5. 1. Synthesis calcium oxide and water CaO(s) + H2O(l)  Ca(OH)2(aq)
sulfur dioxide and water
SO2(g) + H2O(l)  H2SO3(aq)
calcium oxide and sulfur dioxide
CaO(s) + SO2(g)  CaSO3(s)

6. 2. Decomposition opposite of synthesis usually require energy
reactants: only one compound
products: more than one
usually elements but can be compounds
AX  A + X

7. 2. Decomposition water H2O(l)  H2(g) + O2(g) calcium carbonate
CaCO3(s)  CaO(s) + CO2(g)
calcium hydroxide
Ca(OH)2(s)  CaO(s) + H2O(l)
carbonic acid
H2CO3(aq)  CO2(g) + H2O(l)

8. 3. Single Replacement
an element replaces a similar element in a compound
reactants: 1 element & 1 compound
products: 1 element & 1 compound
A + BX  B + AX
Y + AX  X + AY

9. 3. Single Replacement zinc and hydrochloric acid
Zn(s) + HCl(aq)  ZnCl2(aq) + H2(g)
iron and water
Fe(s) + H2O(l)  FeO(aq)
magnesium and lead (II) nitrate
Mg(s) + Pb(NO3)2(aq)  Mg(NO3)3(aq) + Pb(s)
chlorine and potassium bromide
Cl2(g) + KBr(s)  KCl(s) + Br2(g)

10. 4. Double Replacement two similar elements switch places
reactants: 2 compounds
products: 2 compounds
AX + BY  BX + AY

11. 4. Double Replacement barium chloride and sodium sulfate
BaCl2(aq) + Na2SO4(aq)  NaCl(aq) + BaSO4(s)
iron sulfide and hydrochloric acid
FeS(aq) + HCl(aq)  FeCl2(aq) + H2S(g)
hydrochloric acid and sodium hydroxide
HCl(aq) + NaOH  NaCl(aq) + H2O(l)
potassium iodide and lead (II) nitrate
KI(aq) + Pb(NO3)2  KNO3(aq) + PbI2(s)

12. 5. Combustion combines with oxygen
releases energy in form of heat/light
reactants: O2 + compound/element
compound or element must be made of C and H only
H2O and/or CO2
depending on element contained in reactants
Ex: CH4 + O2  CO2 + H2O

13. C3H8(g) + O2(g)  CO2(g) + H2O(g)
Combustion
hydrogen and oxygen
H2(g) + O2(g)  H2O(g)
propane and oxygen
C3H8(g) + O2(g)  CO2(g) + H2O(g)

14. Practice
Classify each of the following reactions one of the five basic types:
Na2O + H2O  NaOH
synthesis
Zn (s) + 2HCl(aq)  ZnCl2(aq) + H2(g)
single replacement
Ca(s) + 2H2O(l)  Ca(OH)2(aq) + H2(g)

15. Practice C2H4(g) + O2(g)  CO2(g) + H2O(g)
2H2O2(aq)  O2(g) + 2H2O(l)
decomposition
Cu(s) + 2AgNO3(aq)  2Ag(s) +Cu(NO3)2(aq)
single replacement
C2H4(g) + O2(g)  CO2(g) + H2O(g)
combustion
ZnO(s) + C(s)  2Zn(s) + CO2(g)

16. Practice Na2O(s) + 2CO2(g) + H2O(l)  NaHCO3(s)
synthesis
Ca(s) + H2O(l)  Ca(OH)2 (aq) + H2(g)
single replacement
KClO3(s)  KCl(s) + O2(g)
decomposition
H2SO4(aq) + BaCl2(aq)  HCl(aq) + BaSO4(s)
double replacement