Unit 7 Chemical Reactions

Types of Reactions

Type of ReactionsChemical reactions are classified into five general types

Synthesis (also called combination or addition)

Decomposition Single Replacement (also called single

displacement) Double Replacement(also called double

displacement) Combustion

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

A + B AB2Mg + O2 2MgO

2Na + Cl2 2NaCl

SO3 + H2O H2SO4

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

Combination (Synthesis) YouTube - Reaction of Sodium & Chlorine

(with subtitles)

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)

Combination (Synthesis) Practice

• Predict the products. Write and balance the following synthesis reaction equations.

• Sodium metal reacts with chlorine gas 2 Na(s) + Cl2(g) 2 NaCl• Solid Magnesium reacts with fluorine gas Mg(s) + F2(g) MgF2• Aluminum metal reacts with fluorine gas 2Al(s) + 3 F2(g) 2AlF3

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.

DecompositionYouTube - ammonium dichromate volcano

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)

Decomposition Practice•Predict the products. Then, write

and balance the following decomposition reaction equations:

•Solid Lead (IV) oxide decomposes PbO2 (s) Pb (s) + O2 (g)

•Aluminum nitride decomposes 2AlN(s) 2 Al (s) + N2 (g)

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

___A. H2 + Br2 2HBr

___B. Al2(CO3)3 Al2O3 + 3CO2

___C. 4 Al + 3C Al4C3

Solution 1Classify the following reactions as 1) combination or 2) decomposition:

_1_A. H2 + Br2 2HBr

_2_B. Al2(CO3)3 Al2O3 + 3CO2

_1_C. 4 Al + 3C Al4C3

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 (-).

Whether one metal will displace another metal from a compound 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)

Single Replacement (Displacement) Practice

•Sodium chloride solid reacts with fluorine gas

2NaCl(s) + F2(g) 2 NaF(s) + Cl2(g)

Note that fluorine (nonmetal) replaces chlorine (nonmetal) in the compound

•Aluminum metal reacts with aqueous copper (II) nitrate

2 Al(s)+ 3Cu(NO3)2(aq) 3Cu(s) + 2 Al(NO3)3

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

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

1_A. 2Al + 3H2SO4 Al2(SO4)3 + 3H2

2_B. Na2SO4 + 2AgNO3 Ag2SO4 + 2NaNO3

1_C. 3C + Fe2O3 2Fe + 3CO

Double Replacement Practice

• Predict the products. Balance the equation

1. HCl(aq) + AgNO3(aq)

2. CaCl2(aq) + Na3PO4(aq)

Double Replacement Practice

• Predict the products. Balance the equation

1. HCl(aq) + AgNO3(aq) HNO3 + AgCl

2. CaCl2(aq) + Na3PO4(aq) Ca3(PO4)2 + NaCl

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•Combustion reactions

occur when a hydrocarbon reacts with oxygen gas.

•This is also called burning!!! In order to burn something you need the 3 things in the “fire triangle”:1) A Fuel (hydrocarbon)2) Oxygen to burn it with3) Something to ignite the reaction (spark)

Products in combustion are ALWAYS carbon dioxide and water. (although incomplete burning does cause some by-products like carbon monoxide)

Combustion PracticeComplete and Balance the combustion

equation

___C5H12 + ___O2

Combustion PracticeBalance the combustion equation

__C5H12 + _8_O2 5CO2 + _6H2O

Unit 8 Chemical Reactions

Types of Reactions