Types of Chemical Reactions

Movie: types of chemical reactions: http://www.youtube.com/watch?v=i-HHvx1VC_8

Learning OutcomesIdentify, give evidence for, predict products of, and classify the following types of chemical reactions:

1. Synthesis (combination)

2. Decomposition

3. Single Replacement

4. Double Replacement

5. Neutralization (acid/base)

6. Combustion

Vocabulary Synthesis

Decomposition

Neutralization

Single displacement

Double displacement

Combustion

A chemical change: any change in which a new substance is formed.

Evidence of a Chemical Change: Release of energy as heat Release of energy as light Change in color Formation of a gas Formation of a precipitate (solid) Change in odor…

Chemical Reactions

1. Neutralization: Acid(H) + Base(OH) salt + H(OH)

2. Combustion: AB + oxygen CO2 + H2O

3. Synthesis: A + B AB

4. Decomposition: AB A + B

5. Single displacement: A + BC AC + B

6. Double displacement: AB + CD AD + CB

Types of Chemical Reactions

–A + B AB where A and B represent elements

– The elements may form ionic compounds, like…

– Sodium metal and chlorine gas combine to form sodium chloride.

– 2Na + Cl2 2NaCl

Sodium added to chlorine gas

Synthesis ReactionsSynthesis reactions are also known as FORMATION reactions.

Two or more reactants (usually elements) join to form a compound.

Synthesis Reactions

Types: Synthesis

Example C + O2

OO C + O O C

OO COO C OO C OO C OO

C OO

C OO

CO

O

C OO

C O

O C O

O C OO C

OO C OO C

General: A + B AB

(c) McGraw Hill Ryerson 2007

OTHER EXAMPLES…1. Elements that form ionic compounds:

Magnesium metal reacts with oxygen gas to form magnesium oxide.• 2Mg + O2 2MgO

2. Elements that form covalent compounds: Nitrogen gas and oxygen gas join to form dinitrogen monoxide.

• 2N2 + O2 2N2O

See pages 258 - 259

Synthesis Reactions

SYNTHESIS REACTION (iron + sulphur):http://www.youtube.com/watch?v=A5H6DVe5FAI

• Decomposition reactions are the opposite of synthesis reactions.– A compounds breaks down into two or more products

(often elements).–AB A + B

where A and B represent elements

1. Ionic compounds may decompose to produce elements, like the following:

• Table salt, sodium chloride, can be broken down into sodium metal and chlorine gas by melting salt at 800ºC and running electricity through it.

• 2NaCl 2Na + Cl2

Decomposition Reactions

(c) McGraw Hill Ryerson 2007 See page 260

Decomposition Reactions

Types: DecompositionExample: NaCl

General: AB A + B

Cl Na Cl + Na

2H2O2 2H2O + O2

Demo Example: H2O2 (hydrogen peroxide)

Types: Decomposition

Example 2HgO

O Hg

O Hg

Hg

O O Hg

+

General: AB A + B

(c) McGraw Hill Ryerson 2007

2. Covalent compounds may decompose into elements, like the following:

• By running electricity through water, the water molecules decompose into hydrogen and oxygen gases.

• 2H2O 2H2 + O2

See page 260

Decomposition Reactions

DECOMPOSITION REACTION:

http://www.youtube.com/watch?v=NddwtXEA_Ak

(c) McGraw Hill Ryerson 2007

• Single replacement reactions replace one element from a compound with another element.– A compound and an element react, and the

element switches places with part of the original compound.• A + BC B + AC where A is a metal, or

• A + BC C + BA where A is a non-metal

See page 261

Single Replacement Reactions

Single Replacement Reactions

Types: Single displacement

Example: Zn + CuCl2

ZnClCl Cu +

General: A+ BC AC + B

ClCl Zn Cu+

Example: Single displacement

Example: 2Na + 2H2O 2NaOH + H2

General: A+ BC AC + B

HOH

Observe what happens

1. When A is a metal:• Aluminum foil in a solution of copper(II)

chloride produces solid copper and aluminum chloride. (We did this in class)

• 2Al + 3CuCl2 3Cu + 2AlCl3

2. When A is a non-metal:• When fluorine is bubbled through a sodium

iodide solution, iodine and sodium fluoride are produced.

• Fl2 + 2NaI I2 + 2NaF

Single Replacement Reactions

SINGLE REPLACEMENT:http://www.youtube.com/watch?v=hKtynbVtMKc

(c) McGraw Hill Ryerson 2007

• Double replacement reactions swap elements between 2 compounds that react together to form two new compounds.– Two compounds react, with elements switching

places between the original compounds. AB + CD AD + CB

See page 262

Double Replacement Reactions

(c) McGraw Hill Ryerson 2007 See page 262

Double Replacement Reactions

Types: Double displacement

Example: MgO + CaS

General: AB + CD AD + CB

SOMg Ca+

O S

Mg Ca+

(c) McGraw Hill Ryerson 2007

– When potassium iodide and lead (II) nitrate react, they form a yellow precipitate, lead (II) iodide, in a solution of potassium nitrate.

– 2KI + Pb(NO3)2 PbI2 + 2KNO3

Double Replacement Reactions

Two solutions react to form a precipitate (solid) and another solution.

Ionic solution + ionic solution ionic solution + ionic solid. AB + CD AD + CB

DOUBLE REPLACEMENT:http://www.youtube.com/watch?v=opY3FLrPTa4

(c) McGraw Hill Ryerson 2007

• Neutralization reactions occur when an acid (most compounds starting with H) and a base (most compounds ending in OH) react to form a salt and water.

• Neutralization reactions are a type of double replacement.

• Acid + base salt + water

HX + MOH MX + H2O where X and M are elements

See page 263

Neutralization Reactions

(c) McGraw Hill Ryerson 2007

1. Sulfuric acid is used to neutralize calcium hydroxide:• H2SO4 + Ca(OH) 2 CaSO4 + 2H2O

2. Phosphoric acid helps to neutralize the compounds that cause rust, such as iron(II) hydroxide.• H3PO4 + 3Fe(OH)2 Fe3(PO4)2 + 6H2O

See page 263

Neutralization Reactions

NEUTRALIZATION:http://www.youtube.com/watch?v=_P5hGzA6Vb0

(c) McGraw Hill Ryerson 2007

• Combustion reactions occur when a compound or element react with oxygen to release energy and produce an oxide.– Also sometimes referred to as hydrocarbon

combustion.

CXHY + O2 CO2 + H2O where X and Y represent integers

See page 264

Combustion Reactions

METHANOL + oxygen: http://www.youtube.com/watch?v=98JuJ-G1qXY&feature=related

(c) McGraw Hill Ryerson 2007

1. Natural gas (methane) is burned in furnaces to heat homes.

»CH4 + O2 CO2 + 2H2O + energy

2. An acetylene torch is used to weld metals together.

»2C2H2 + 5O2 4CO2 + 2H2O + energy

3. Carbohydrates like glucose combine with oxygen in our body to release energy.

»C6H12O6 + 6O2 6CO2 + 6H2O + energy See page 264

Acetylene torch

Combustion Reactions

(c) McGraw Hill Ryerson 2007 See page 265

Take the Section 6.1 Quiz

SUMMARY OF REACTIONSMOVIE TO REVIEW: http://www.bcscience.com/bc10/pgs/videos_013_chemical_reactions.html