Types of Chemical Types of Chemical ReactionsReactions

OutlineOutline

Types of Reactions – the 5 typesTypes of Reactions – the 5 types Synthesis and DecompositionSynthesis and Decomposition

Chemical ReactionsChemical Reactions

Chemical reactions can be grouped Chemical reactions can be grouped into five categories:into five categories:

Synthesis/CombinationSynthesis/Combination DecompositionDecomposition Single displacementSingle displacement Double displacementDouble displacement CombustionCombustion

Chemical ReactionsChemical Reactions

Today we will focus on synthesis and Today we will focus on synthesis and decompositiondecomposition

LEARNING GOAL:LEARNING GOAL:Be able to identify and predict the Be able to identify and predict the

products for synthesis and products for synthesis and decomposition reactionsdecomposition reactions

Synthesis ReactionSynthesis Reaction

Synthesis ReactionSynthesis Reaction – Two or more – Two or more substances (elements or compounds) react substances (elements or compounds) react to form ONE product. Combination of to form ONE product. Combination of smaller atoms/molecules into larger smaller atoms/molecules into larger molecules.molecules.

Usually exothermic (energy is produced)Usually exothermic (energy is produced) Can occur naturally or by an initial Can occur naturally or by an initial

application of energy (heat, flame, UV light, application of energy (heat, flame, UV light, use of catalyst)use of catalyst)

Synthesis ReactionSynthesis Reaction

AA + + BB AABB

eg. 2eg. 2HH22 + + OO22 2 2HH2200

22Na Na (s)(s) + + ClCl2(g)2(g) 2 2NaNaCl Cl (s)(s) + energy+ energy

Synthesis ReactionSynthesis Reaction

Predicting Products

Metal + oxygen → metal oxide (basic oxide)EX. 2Mg(s) + O2(g) → 2MgO(s)

Nonmetal + oxygen → nonmetallic oxide (acidic oxide)EX. C(s) + O2(g) → CO2(g)

Metal oxide + water → metallic hydroxide (base)EX. MgO(s) + H2O(l) → Mg(OH)2(s)

Nonmetallic oxide + water → acid EX. CO2(g) + H2O(l) → ; H2CO3(aq)

Metal + nonmetal → salt EX. 2 Na(s) + Cl2(g) → 2NaCl(s)

A few nonmetals combine with each other. EX. 2P(s) + 3Cl2(g) → 2PCl3(g)

These two reactions must be remembered: N2(g) + 3H2(g) → 2NH3(g)

NH3(g) + H2O(l) → NH4OH(aq)

Decomposition ReactionDecomposition Reaction

Decomposition Reaction – ONE reactant Decomposition Reaction – ONE reactant produces two or more products. Splitting of produces two or more products. Splitting of large molecules into elements or smaller large molecules into elements or smaller molecules.molecules.

Usually endothermic (requires energy)Usually endothermic (requires energy) Can require energy in the form of heat, Can require energy in the form of heat,

electricity, catalyst, UV lightelectricity, catalyst, UV light *some decomposition rxns occur at room *some decomposition rxns occur at room

temperaturetemperature

Decomposition ReactionDecomposition Reaction

AABB AA + + BB

Eg. Eg. 22HH220 0 22HH22 + + OO22

22NaNaCl Cl (s) (s) 2 2Na Na (s)(s) + + ClCl2(g)2(g) (heat/electricity required)(heat/electricity required)

Decomposition ReactionDecomposition Reaction

Predicting ProductsMetallic carbonates, when heated, form metallic oxides and CO2(g).

EX. CaCO3(s) → CaO(s) + CO2(g) Most metallic hydroxides, when heated, decompose into metallic oxides and water.

EX. Ca(OH)2(s) → CaO(s) + H2O(g) Metallic chlorates, when heated, decompose into metallic chlorides and oxygen.

EX. 2KClO3(s) → 2KCl(s) + 3O2(g) Some acids, when heated, decompose into nonmetallic oxides and water.

EX. H2SO4 → H2O(l) + SO3(g) Some oxides, when heated, decompose.

EX. 2HgO(s) → 2Hg(l) + O2(g) Some decomposition reactions are produced by electricity.

EX. 2H2O(l) → 2H2(g) + O2(g)

EX. 2NaCl(l) → 2Na(s) + Cl2(g)