Unit 7 Chemical Reactions

Types of Reactions

Type of ReactionsChemical reactions are classified into five general types

Synthesis (Combination) Two or more elements or simple compounds combine to form (synthesize) one product

A + B AB2Mg + O2 2MgO

2Na + Cl2 2NaCl

When two elements combine in synthesis, the product is a compound made of their respective ions.

SynthesisYouTube - Reaction of aluminium with

bromine

Synthesis (practice)• Predict the products. Write and balance

the following synthesis reaction equations.• Sodium metal reacts with chlorine gas Na(s) + Cl2(g) • Solid Magnesium reacts with fluorine gas Mg(s) + F2(g) • Aluminum metal reacts with fluorine gas Al(s) + F2(g)

DecompositionOne substance is broken down (split) into two or more simpler substances.

AB A + B

2HgO 2Hg + O2

2KClO3 2KCl + 3 O2

a compound made of two elements, decomposes into those elements.

Decomposition

Decomposition Practice•Predict the products. Then, write

and balance the following decomposition reaction equations:

•Solid Lead (IV) oxide decomposes PbO2(s)

•Aluminum nitride decomposes AlN(s)

Learning Check 1Classify the following reactions as 1) synthesis or 2) decomposition:

___A. H2 + Br2 2HBr

___B. Al2(CO3)3 Al2O3 + 3CO2

___C. 4 Al + 3C Al4C3

CombustionA reaction in which a hydrocarbon (compound made up of H and C) reacts with oxygen and the products are carbon dioxide and water

CH4 + 2O2 CO2 + 2H2O

C3H8 + 5O2 3CO2 + 4H2O

Combustion PracticeComplete and Balance the combustion

equation

___C5H12 + ___O2

Single Replacement (Displacement)One element takes the place of an element in a reacting compound.

A + BC AC + B

Zn + 2HCl ZnCl2 + H2

Fe + CuSO4 FeSO4 +

Cu

A metal can replace a metal (+) OR a nonmetal

can replace a nonmetal (-).

Depends on the relative reactivity's of the two

metals.

Single Replacement (Displacement) Practice

YouTube - Thermite reaction

Single Replacement Displacement)

The activity series of metals lists metals in order of decreasing reactivity.

A metal will replace any metal listed below.

Lithium

Potassium

Calcium

Sodium

Magnesium

Aluminum

Zinc

Iron

Lead

Hydrogen

Copper

Mercury

silver

Single Replacement (Displacement) Practice

•Sodium chloride solid reacts with fluorine gas

NaCl(s) + F2(g)

•Aluminum metal reacts with aqueous copper (II) nitrate

Al(s)+ Cu(NO3)2(aq)

Double Replacement (Displacement)

Two elements in reactants take the place of each other

AB + CD AD + CB

AgNO3 + NaCl AgCl +

NaNO3

ZnS + 2HCl ZnCl2 +

H2S

Double Replacement (Displacement)

YouTube - Double Replacement Reactions

• Think about it like “foil”ing in algebra, first and last ions go together ; inside ions go together

• Example:

AgNO3(aq) + NaCl(s) AgCl(s) + NaNO3(aq)

• Another example:

K2SO4(aq) + Ba(NO3)2(aq) KNO3(aq) + BaSO4(s)

Classify the following reactions as 1) single replacement 2) double replacement

__A. 2Al + 3H2SO4 Al2(SO4)3 + 3H2

__B. Na2SO4 + 2AgNO3 Ag2SO4 + 2NaNO3

__C. 3C + Fe2O3 2Fe + 3CO

Double Replacement Practice

• Predict the products. Balance the equation

1. HCl(aq) + AgNO3(aq)

2. CaCl2(aq) + Na3PO4(aq)

Unit 8 Chemical Reactions

Types of Reactions