C hemistry The study of matter and the CHANGES it undergoes shastacollege.edu

The Law of Conservation of Mass Mass can neither be created nor destroyed in any chemical process. The mass at the start of a chemical reaction must equal the mass at the end of the reaction.

Synthesis Reactions zaka: Direct Combination Reaction zTwo substances combine to form one new, more complex substance 

Synthesis Reactions z Form: A + B AB z2 Mg (s) + O 2 (g) 2MgO (s)

Decomposition Reactions za.k.a. Analysis Reactions zone complex substance breaks down into two or more “simpler” substances zUsed to determine % composition of substances in laboratories.

Decomposition Reactions Form: AB  A + B 2 HCl (aq)  H 2 (g) + Cl 2 (g) 

Combustion Reactions zO 2 (g) and an organic molecule of carbon, hydrogen and oxygen react zCO 2 (g) and H 2 O (g) are produced

Combustion Reactions zForm: C x H y O z + O 2 (g)  CO 2 (g) + H 2 O (g) zC 3 H 8 (g) + 5O 2 (g)  3CO 2 (g) + 4H 2 O (g)

Single Replacement Reactions: Cation Replacements zA metal element becomes a cation in solution and the cation that was in solution becomes a neutral element. zAKA. Oxidation-Reduction Reactions zThe ATOM must be more active than the ION for the reaction to occur. zReactions based upon Activity Series ranking of elements

Single Replacement Reactions zForm: A + BXAX + B zLi(s) + AuCl(aq)  LiCl(aq) + Au(s)

Red-Ox Reactions Loss of Gain of ElectronsElectrons OxidationReduction LEO goes GER Li(s) + AuCl(aq)  LiCl(aq) + Au(s) Li (s)  Li e - Lost e - = oxidation Au e -  AuGained e - =reduction

Double Displacement Reactions zThe cations of two aqueous ionic compounds switch with each other. zEither water, a gas or an insoluble product must be formed,otherwise there is no reaction. zIf water is produced, an acid has reacted with a base.

Double Displacement Reactions zForm: AX + BY  AY + BX zHCl (aq) + NaOH (aq)  H 2 O (l) + NaCl (aq) zPb(NO 3 ) 2 (aq) + 2KI (aq)  PbI 2 (s) + 2KNO 3 (aq)

Identify The TYPES of these Reactions z9 O 2 (g)+ C 6 H 12 (l)  6 CO 2 (g) + 6 H 2 O (l) z2 H 2 O (g)  2 H 2 (g) + O 2 (g) z2 Na(s) + 2 HCl (aq)  H 2 (g)+ 2 NaCl(aq) O 2 is a reactant, CO 2 and H 2 O are products… must be… One compound breaks up unto two less complex substances… must be… A metal reacts with an aqueous solution to produce… a new solution and an element Must be… combustion Decomposition (or analysis) Single displacement

Five more to ID… z4) HCl (aq) + NaOH (aq)  NaCl (aq) + H 2 O(l) z5) 3 H 2 (g) + N 2 (g)  2NH 3 (g) z6) LiI (aq) + AgNO 3 (aq)  LiNO 3 (aq)+ AgI (s) z7) Na (s) + AgNO 3 (aq)  NaNO 3 (aq) + Ag(s) z8) H 2 CO 3 (aq)  H 2 O (l) + CO 2 (g) Double Replacement Synthesis Double Replacement Single Replacement Decomposition

Octane (C 8 H 18 ) and oxygen gas (O 2 ) combust C 8 H 18 (g) + O 2 (g)  CO 2 (g) + H 2 O (g) Balance Carbons C 8 H 18 (g) + O 2 (g)  8 CO 2 (g) + H 2 O (g) Balance Hydrogens C 8 H 18 (g) + O 2 (g)  8 CO 2 (g) + 9H 2 O (g) Balance Oxygens C 8 H 18 (g) O 2 (g)  8 CO 2 (g) + 9 H 2 O (g) Double Everything 2 C 8 H 18 (g) + 25 O 2 (g)  16 CO 2 (g) + 18 H 2 O (g) CH O Reactants Products Reactants Products Reactants Products Reactants Products

zSolid sodium reacts with aqueous silver nitrate in a single replacement reaction. Na (s) + AgNO 3 (aq)  Ag (s) + NaNO 3 (aq) Hey… it’s already balanced!

Aqueous copper (II) chloride reacts with aqueous silver nitrate in a double replacement reaction. CuCl 2 (aq) + NaOH (aq)  NaCl (aq) + Cu(OH) 2 (s) CuCl 2 (aq) + 2NaOH (aq)  2NaCl (aq) + Cu(NO 3 ) 2 (s)