CLASSIFYING CHEMICAL REACTIONS

FIVE BASIC WAYS TO CLASSIFY CHEMICAL REACTIONS:

1. Synthesis

2. Decomposition

3. Single-Replacement

4. Double-Replacement

5. Combustion

Synthesis Reactions:

• Generic Reaction • X + Y-->XY

• Definition-In this equation, X and Y can be compounds or elements. The

result XY is a compound.

2 Rectants and 1 Product

Analogy- Like a marriage

Examples of Real Synthesis Reactions:

• 2Ba + O2 -->2BaO

• 4Cu+ + O2 ->2Cu2O

• 2Cu+ O2 >2CuO

• 2H2 + O2 -->2H2O

• C + O2 -->CO2

• 2Na + Cl2 -->2NaCl2

Decomposition Reactions:

• In a decomposition reaction, an element or

compound is broken down into two simpler

substances. The generic formula of a

decomposition reaction is:

• XY --> X + Y • Decomposition reactions

are the opposite of synthesis reactions. 1 Reactant and 2 Products

Analogy-Like divorce

Examples of Real Decomposition Reactions:

• 2HgO --> 2Hg + O2

• 2H2O --> 2H2 + O2

• CaCO3 --> CaO + CO2

• Cu(OH)2 --> CuO +

H2O

• 2KClO3 --> 2KCl + 3O2

H2SO4 --> SO3 + H2O

Single Replacement Reactions:

• In this type of reaction, one

element replaces a similar element in a

compound. • A + XY --> AY + X • In this equation, A,

X, and Y are the elements and XY,

AY, and XA are the compounds.

1 free element + compound compound + 1 free element

Aggressive metal wins

Like finding a new girl friend

Examples of Single Replacement Reactions:

• 2Al + 3Fe(NO3)2 3Fe + 2Al(NO3)3

• Zn + CuCl2 • Mg + Pb(NO3)2 • Fe + Na3PO4 • 2K + ZnCl2

Metal Reactivity ChartLi Rb K Ca Na Mg Al Mn Zn Fe Ni Sn PbH

Cu Ag PtAu

Most aggressive metal (woman) wins out

Examples of Real Single Replacement Reactions:

• 2Al + 3Fe(NO3)2 3Fe + 2Al(NO3)3

• Zn + CuCl2 Cu + ZnCl2 • Mg + Pb(NO3)2 Pb + Mg (NO3)2 • Fe + Na3PO4 N.R.• 2K + ZnCl2 2 KCl + Zn

• Cl2 + 2KBr 2KCl + Br2

Double-Replacement Reactions:

• In a double-replacement reaction, the two compounds

exchange places in a solution to form two

new compounds. The general equation of a double-replacement

reaction is: • AB + XY --> AY + XB

2 compounds 2 compounds

Like switching partners in square dancing

Examples of Real Double-Replacement

Reactions:• Pb(NO3)2 + 2KI --> PbI2 + 2KNO3

• FeS + 2HCl --> H2S + FeCl2

• HCl + NaOH --> NaCl + H2O

“lets take turns dancing with these two beautiful ladies”

Combustion Reactions:

• When a substance combines with

oxygen releasing in a large amount of energy in the form of light and heat, it

is a combustion reaction.

Oxygen is needed to Burn things.

Generic

C + O2 CO2 + heat

Examples of Real Combustion Reactions:• examples of combustion reactions

• C3H8 + 5O2 --> 3CO2 + 4H2O + heat

• 2CH4 + 4O2 2CO2 + 4H2O + heat

FIVE BASIC WAYS TO CLASSIFY CHEMICAL REACTIONS:

1. Synthesis 2 reactants1 product (like marriage)

2. Decomposition 1 reactant 2 products (like

divorce) 3. Single-Replacement (most aggressive element

wins)

4. Double-Replacement (switch partners)

5. Combustion=Burning (need oxygen to burn things)