Types of Chemical Reactions

Types of Chemical ReactionsSynthesis

Decomposition

Single Displacement

Double Displacement

Combustion

Neutralization

http://www.youtube.com/watch?v=tE4668aarck&feature=player_embedded

Synthesis Reactions• In a synthesis reaction, two simple reactants combine to make a

larger or more complex product• The general pattern for a synthesis reaction is

A + B→ AB

•  A and B can be elements or compounds, AB is a compound.

Examples of synthesis reactions:

4 Al(s) + 3 O2(g) → 2 Al2O3(s)

2Mg+O2→2MgO

2Na+Cl2→2NaCl

CaO+ H2O→ Ca(OH)2

Hydrogen chloride + ammonia → ammonium chloride

Decomposition ReactionsDecomposition Reaction- A reaction in which a large or more

complex molecule breaks down to form two (or more) simpler products

 -represented by this general equation:

AB→ A + B

AB is a compound, A and B can be elements or compounds

Examples of Decomposition Reactions:

2MgO→2Mg+O2

Ca(OH)2→ CaO+ H2O

H2SO4→SO3+ H2O

2H2O→2H2+ O2

 

 

• You must be able to recognize what type of reaction depending on the reactants and product.

• DON’T FORGET THAT SOME ELEMENTS EXIST AS DIATOMIC MOLECULES!!!

• H2, O2, N2, F2, Cl2, Br2, I2

Single Displacement Reactions

Single Displacement Reaction-a reaction in which an element displaces another element in a compound, producing a new compound and a new element

-one element takes the place of (displaces) another element in a compound

-usually metals displace metals, and non metals displace non metals

 -represented by this general equation:

A + BC → B + AC

 

Examples of Single Displacement Reactions:Mg+ 2AgNO3 -> 2Ag + Mg(NO3)2 (silver and magnesium are both metals, magnesium

displaces silver) Br2 + CaI2→CaBr2 + I2

(Bromine displaces Iodine. Bromine and Iodine are both non-metals that have negative ionic charges)

 3CuCl2 +2Al→ 2AlCl3 +3Cu(Aluminum, a metal, displaces copper, a metal) Mg +2HCl→ H2+ MgCl2

(Magnesium, a metal, displaces Hydrogen, acting as a metal)

 

Double Displacement Reactions

Double Displacement Reactions-a reaction that

occurs when elements in different compounds

displace each other or exchange places, producing

2 new compounds

-the METALS (cations) of two compounds exchange

places-a precipitate, a gas or a molecular compound is

usually formed

-represented by this general equation:

AB + CD → AD+ CB

Examples of Double Displacement Reactions:

2KI + Pb(NO3)2→PbI2+ 2KNO3

 

FeS + 2HCl→ H2S + FeCl2 

Pb (NO3)2 + K2CrO4 → PbCrO4 + 2KNO3

COMBUSTION• Combustion reactions always

involve molecular oxygen O2. Anytime anything burns (in the usual sense), it is a combustion reaction.

• Combustion reactions almost always give off heat. For example when wood burns, it must do so in the presence of O2 and a lot of heat is produced:

• For example consider the combustion of methanol (rubbing alcohol):

• Of course, not all combustion reactions release CO2 and water, e.g., the combustion of magnesium metal: