5.1 and 5.2 DESCRIBING CHEMICAL

REACTIONS

TYPES OF CHEMICAL REACTIONS

• chemists use patterns to classify reactions into the following groups:

• Synthesis• Decomposition• Single displacement• Double displacement

SYNTHESIS REACTIONS

• the combination of smaller molecules to create a more complex molecule

• General Formula:A + B AB

SYNTHESIS REACTION

A + B AB

+

Example

Sodium + Bromine Sodium bromide

Na + Br2 NaBr

Na+ Br- Br-Na+

DECOMPOSITION REACTIONS

• these reactions are the opposite of synthesis reactions

• they involve a compound breaking down into elements

• General Formula:AB A + B

DECOMPOSITION REACTION

AB A + B

+

Example

Lithium fluoride Lithium + Fluorine gas

LiF Li + F2

Li+ F-Li+ F-

SINGLE DISPLACEMENT REACTIONS

• reactions involving an element and a compound as reactants

• the element replaces one of the elements in the compound

• General Formula: A + BC AC + B

+ - + -

SINGLE DISPLACEMENT REACTION

+

A + BC AC + B

+

Example

Lithium + Sodium chloride Lithium chloride + Sodium

Li + NaCl LiCl + Na Na+ Cl-Li+ Na-Li+ Cl-

DOUBLE DISPLACEMENT REACTIONS

• reactions in which elements exchange places in two compounds

General Formula:

AB + CD AD + CB+ - + - + - + -

DOUBLE DISPLACEMENT REACTION

+

AB + CD AD + CB

+

Example

Sodium chloride + Lithium fluoride Sodium fluoride + Lithium chloride

NaCl + LiF NaF + LiCl

Na+ Cl- Li+ F- Na+ F- Li+ Cl-

Identify the "type" for each reaction below:

1. Ca + O2  CaO

2. Br2 + LiI  LiBr + I2

3. Al + Fe(NO3)2  Al(NO3)3 + Fe

4. MgO + HCl  MgCl2 + H2O

5. H2CO3  CO2 + H2O

6. H2 + O2  H2O

7. (NH4)3PO4 + Sr(OH)2 Sr3(PO4)2 + NH4OH

Synthesis

Single displacement

Decomposition

Single displacement

Double displacement

Synthesis

Double displacement

HOMEWORK

• Read p.179 -189 and complete Q 1-8 (p. 189)

• Read 190-198 and complete Q 1, 2, 4, 6, 7 (p. 198)

• Complete “Types of Chemical Reactions” WS#16