Types of ReactionsUnit C – Chemical Reactions

Chemical reaction: a process in which substances interact, causing new substances with different properties to form

Reactant: a starting substance in a chemical reaction

Product: a substance that is formed in a chemical reaction

Chemical equations

Chemical equation: a condensed statement that expresses chemical change using symbols and chemical names or formulas

Word equation: a chemical equation in which the reactants and products in a chemical reaction are represented by their chemical names; their relative quantities or states of matter are not included

Chemical equations

Skeleton equation: a chemical equation in which the reactants and products in a chemical reaction are represented by their chemical formulas; their relative quantities or states of matter are not included

Balanced chemical equation: a statement that uses chemical formulas and coefficients to show the identities and ratios of the reactants and products in a chemical reaction

Chemical equations

Coefficient: in a balanced chemical equation, a positive number that is placed in front of a formula to show the relative number of particles of the substance that are involved in the reaction

Example #1iron + oxygen iron(III) oxideFe(s)+ O2(g) Fe2O3(s)

Chemical equations

There are generally 5 types of chemical reactions:1) Synthesis2) Decomposition3) Combustion4) Single displacement5) Double displacement

Chemical reactions

Synthesis reaction: a chemical reaction in which two or more reactants combine to produce a single compound

There are 3 general types of synthesis reactions:1) 2 elements react to form a binary compound2) 1 element reacts with 1 compound to form a

new compound3) 2 compounds react to form a new compound

Synthesis

2 elements react to form a binary compound◦ A univalent metal reacts with a non-metal to

form an ionic compound

Example #12 Na(s) + Cl2(g) 2 NaCl(s)

Synthesis

2 elements react to form a binary compound◦ A multivalent metal reacts with a non-metal to

form various ionic compounds

Example #12 Cu(s) + Cl2(g) 2 CuCl(s)

Example #2Cu(s) + Cl2(g) CuCl2(s)

Synthesis

2 elements react to form a binary compound◦ Two non-metals react to form a molecular

compound

Example #1C(s) + O2(g) CO2(g)

Example #22 C(s) + O2(g) 2 CO(g)

Synthesis

1 element reacts with 1 compound to form a new compound

Example #12 SO2(g) + O2(g) 2 SO3(g)

Example #2PCl3(ℓ) + Cl2(g) PCl5(s)

Synthesis

2 compounds react to form a new compound◦ A non-metal oxide reacting with water to form

an acid

Example #1CO2(g) + H2O(ℓ) H2CO3(aq)

Example #2SO3(g) + H2O(ℓ) H2SO4(aq)

Synthesis

2 compounds react to form a new compound◦ A metal oxide reacting with water to form a

base

Example #1Na2O(s) + H2O(ℓ) 2 NaOH(aq)

Example #2MgO(s) + H2O(ℓ) Mg(OH)2(aq)

Synthesis

Decomposition reaction: a chemical reaction in which a compound breaks down into elements or simpler compounds

There are 4 general types of decomposition reactions (and a few special ones):1) A binary compound decomposing into its elements2) A metal nitrate decomposing into a metal nitrite and

oxygen gas3) A metal carbonate decomposing into a metal oxide

and carbon dioxide4) A metal hydroxide decomposing into a metal oxide

and water5) Special reactions

Decomposition

A binary compound decomposing into its elements

Example #12 NaCl(s) 2 Na(s) + Cl2(g)

Example #22 HgO(s) 2 Hg(ℓ) + O2(g)

A metal hydroxide decomposing into a metal oxide and water

Example #1Ca(OH)2(s) CaO(s) + H2O(g)

Decomposition

A metal nitrate decomposing into a metal nitrite and oxygen gas

Example #12 NaNO3(s) 2 NaNO2(s) + O2(g)

A metal carbonate decomposing into a metal oxide and carbon dioxide

Example #1CaCO3(s) CaO(s) + CO2(g)

Sr(OH)2 (s) H2O(l) + SrO(s)

Decomposition

Special reactions◦ TNT (tri-nitro-toluene), dynamite

Example #12 C7H5N3O6(s) 3 N2(g) + 5 H2O(g) + 7 CO(g) + 7 C(s)

◦ Air bags (sodium azide):

Example #12 NaN3(s) 2 Na(s) + 3 N2(g)

Decomposition

Special reactions◦ Rocket thrusters (hydrazine):

Example #13 N2H4(ℓ) 4 NH3(g) + N2(g)

N2H4(ℓ) N2(g) + 2 H2(g)

Decomposition

Combustion reaction: the reaction of a substance with oxygen, producing one or more oxides, heat, and light

Hydrocarbon: a compound that is composed only of the elements carbon and hydrogen

There are 2 general types of combustion of hydrocarbon reactions:1) Complete combustion2) Incomplete combustion

Combustion

Prefixes used in naming hydrocarbonsNumber of

carbon atoms

PrefixAlkane

(CnH2n+2)Formula

1 Meth~ Methane CH4

2 Eth~ Ethane C2H6

3 Prop~ Propane C3H8

4 But~ Butane C4H10

5 Pent~ Pentane C5H12

6 Hex~ Hexane C6H14

7 Hept~ Heptane C7H16

8 Oct~ Octane C8H18

9 Non~ Nonane C9H20

10 Dec~ Decane C10H22

Combustion

Complete combustion occurs when the only products are carbon dioxide (CO2) and water (H2O)

Example #1C3H8(g) + O2(g) CO2(g) + H2O(ℓ)

Combustion

Incomplete combustion occurs when the products are carbon dioxide (CO2) and water (H2O) AS WELL AS carbon monoxide (CO) and carbon/soot (C)

Soot: fine particles consisting mostly of carbon, formed during the incomplete combustion of a hydrocarbon

Example #12 C3H8(g) + 7 O2(g) 2 CO2(g) + 8 H2O(ℓ) + 2 CO(g) + 2 C(s)

2 C3H8(g) + 7 O2(g) CO2(g) + 8 H2O(ℓ) + 4 CO(g) + C(s)

2 C3H8(g) + 6 O2(g) CO2(g) + 8 H2O(ℓ) + 2 CO(g) + 3 C(s)

Combustion

Combustion reactions can also occur between oxygen and many other substances

Some of these reactions are not only combustion reactions, but synthesis reactions as well

Example #12 H2(g) + O2(g) 2 H2O(g)

Example #22 Mg(s) + O2(g) 2 MgO(s)

Combustion

Combustion also occurs inside living organisms

An example of this is the combustion of glucose which is a chemical reaction necessary for life (cellular respiration)

Example #1C6H12O6(s) + O2(g) 6 CO2(g) + 6 H2O(g)

Although both combustion and cellular respiration are similar chemical reactions, there are some notable differences among the two processes

Combustion

Characteristics CombustionCellular

RespirationSpeed Is a faster process Is a slower process

TemperatureGenerally occurs at high temperatures

Occurs at body temperatures

Complete/incomplete

reaction

May be incomplete, producing soot and carbon monoxide

Always complete, producing carbon dioxide, water, and

energy

DurationIs not a continuous

processOccurs at all times within living cells

Combustion

Single displacement reaction: a chemical reaction in which one element in a compound is replaced (displaced) by another element

Activity series (metal & non-metal): a ranking of the relative reactivity of metals or halogens in aqueous reactions

There are 3 general types of single displacement reactions:1) A metal displacing another metal from an ionic compound

(involves activity series of metals)2) A metal displacing hydrogen from acid or water (involves

activity series of metals)3) A non-metal displacing another non-metal from an ionic

compound (involves activity series of non-metals)

Single displacement

A metal displacing another metal from an ionic compound (involves activity series of metals)

Example #1Cu(s) + 2 AgNO3(aq) Cu(NO3)2(aq) + 2 Ag(s)

Example #2Cu(s) + Al(NO3)3(aq) No reaction

Single displacement

A metal displacing hydrogen from acid or water (involves activity series of metals)

Example #1Mg(s) + 2 HCl(aq) MgCl2(aq) + H2(g)

Example #2Na(s) + H2O(ℓ) NaOH(aq) + H2(g)

Example #3Cu(s) + HCl(aq) No reaction

Single displacement

A non-metal displacing another non-metal from an ionic compound (involves activity series of non-metals)

Example #1Cl2(g) + 2 NaBr(aq) 2 NaCl(aq) + H2(g)

Single displacement

[organizational chart summarizing all 5 types and subcategories]

Chemical reactions

[include 2010 and 2003 MHR Chemistry 11 textbooks]

References