Unit 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 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

 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

 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 #1 iron+oxygen  iron(III) oxide Fe(s)+O 2 (g)  Fe 2 O 3 (s)

 There are generally 5 types of chemical reactions: 1)Synthesis 2)Decomposition 3)Combustion 4)Single displacement 5)Double displacement

 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 compound 2)1 element reacts with 1 compound to form a new compound 3)2 compounds react to form a new compound

 2 elements react to form a binary compound ◦ A univalent metal reacts with a non-metal to form an ionic compound Example #1 2 Na(s) + Cl 2 (g)  2 NaCl(s)

 2 elements react to form a binary compound ◦ A multivalent metal reacts with a non-metal to form various ionic compounds Example #1 2 Cu(s) + Cl 2 (g)  2 CuCl(s) Example #2 Cu(s) + Cl 2 (g)  CuCl 2 (s)

 2 elements react to form a binary compound ◦ Two non-metals react to form a molecular compound Example #1 C(s) + O 2 (g)  CO 2 (g) Example #2 2 C(s) + O 2 (g)  2 CO(g)

 1 element reacts with 1 compound to form a new compound Example #1 2 SO 2 (g) + O 2 (g)  2 SO 3 (g) Example #2 PCl 3 (ℓ) + Cl 2 (g)  PCl 5 (s)

 2 compounds react to form a new compound ◦ A non-metal oxide reacting with water to form an acid Example #1 CO 2 (g) + H 2 O(ℓ)  H 2 CO 3 (aq) Example #2 SO 3 (g) + H 2 O(ℓ)  H 2 SO 4 (aq)

 2 compounds react to form a new compound ◦ A metal oxide reacting with water to form a base Example #1 Na 2 O(s) + H 2 O(ℓ)  2 NaOH(aq) Example #2 MgO(s) + H 2 O(ℓ)  Mg(OH) 2 (aq)

 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 elements 2)A metal nitrate decomposing into a metal nitrite and oxygen gas 3)A metal carbonate decomposing into a metal oxide and carbon dioxide 4)A metal hydroxide decomposing into a metal oxide and water 5)Special reactions

 A binary compound decomposing into its elements Example #1 2 NaCl(s)  2 Na(s) + Cl 2 (g) Example #2 2 HgO(s)  2 Hg(ℓ) + O 2 (g)  A metal hydroxide decomposing into a metal oxide and water Example #1 Ca(OH) 2 (s)  CaO(s) + H 2 O(g)

 A metal nitrate decomposing into a metal nitrite and oxygen gas Example #1 2 NaNO 3 (s)  2 NaNO 2 (s) + O 2 (g)  A metal carbonate decomposing into a metal oxide and carbon dioxide Example #1 CaCO 3 (s)  CaO(s) + CO 2 (g) Sr(OH) 2 (s)  H 2 O (l) + SrO(s)

 Special reactions ◦ TNT (tri-nitro-toluene), dynamite Example #1 2 C 7 H 5 N 3 O 6 (s)  3 N 2 (g) + 5 H 2 O(g) + 7 CO(g) + 7 C(s) ◦ Air bags (sodium azide): Example #1 2 NaN 3 (s)  2 Na(s) + 3 N 2 (g)

 Special reactions ◦ Rocket thrusters (hydrazine): Example #1 3 N 2 H 4 (ℓ)  4 NH 3 (g) + N 2 (g) N 2 H 4 (ℓ)  N 2 (g) + 2 H 2 (g)

 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 combustion 2)Incomplete combustion

Prefixes used in naming hydrocarbons Number of carbon atoms PrefixAlkane (C n H 2n+2 )Formula 1Meth~MethaneCH 4 2Eth~EthaneC2H6C2H6 3Prop~PropaneC3H8C3H8 4But~ButaneC 4 H 10 5Pent~PentaneC 5 H 12 6Hex~HexaneC 6 H 14 7Hept~HeptaneC 7 H 16 8Oct~OctaneC 8 H 18 9Non~NonaneC 9 H 20 10Dec~DecaneC 10 H 22

 Complete combustion occurs when the only products are carbon dioxide (CO 2 ) and water (H 2 O) Example #1 C 3 H 8 (g) + O 2 (g)  CO 2 (g) + H 2 O(ℓ)

 Incomplete combustion occurs when the products are carbon dioxide (CO 2 ) and water (H 2 O) 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 #1 2 C 3 H 8 (g) + 7 O 2 (g)  2 CO 2 (g) + 8 H 2 O(ℓ) + 2 CO(g) + 2 C(s) 2 C 3 H 8 (g) + 7 O 2 (g)  CO 2 (g) + 8 H 2 O(ℓ) + 4 CO(g) + C(s) 2 C 3 H 8 (g) + 6 O 2 (g)  CO 2 (g) + 8 H 2 O(ℓ) + 2 CO(g) + 3 C(s)

 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 #1 2 H 2 (g) + O 2 (g)  2 H 2 O(g) Example #2 2 Mg(s) + O 2 (g)  2 MgO(s)

 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 #1 C 6 H 12 O 6 (s) + O 2 (g)  6 CO 2 (g) + 6 H 2 O(g)  Although both combustion and cellular respiration are similar chemical reactions, there are some notable differences among the two processes

CharacteristicsCombustionCellular Respiration SpeedIs a faster processIs a slower process Temperature Generally 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 Duration Is not a continuous process Occurs at all times within living cells

 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)

 A metal displacing another metal from an ionic compound (involves activity series of metals) Example #1 Cu(s) + 2 AgNO 3 (aq)  Cu(NO 3 ) 2 (aq) + 2 Ag(s) Example #2 Cu(s) + Al(NO 3 ) 3 (aq)  No reaction

 A metal displacing hydrogen from acid or water (involves activity series of metals) Example #1 Mg(s) + 2 HCl(aq)  MgCl 2 (aq) + H 2 (g) Example #2 Na(s) + H 2 O(ℓ)  NaOH(aq) + H 2 (g) Example #3 Cu(s) + HCl(aq)  No reaction

 A non-metal displacing another non-metal from an ionic compound (involves activity series of non-metals) Example #1 Cl 2 (g) + 2 NaBr(aq)  2 NaCl(aq) + H 2 (g)

 [organizational chart summarizing all 5 types and subcategories]

 [include 2010 and 2003 MHR Chemistry 11 textbooks]