2 Five Types of Chemical Reactions Remember…a chemical reaction is when one compound is changed into a totally different compound.While there are millions of different types of reactions, they can all be classified into five general types.
3 Five Types of Chemical Reactions The five types are:SynthesisDecompositionSingle ReplacementDouble replacementCombustion
4 Synthesis ReactionA synthesis reaction takes place when two or more chemicals react to produce a single chemical.The reactants can be either elements or molecules (the product is always a molecule).A + B AB
6 Practical use – the synthesis of nylon Synthesis ReactionPractical use – the synthesis of nylonA key ingredient in toothbrushes, tents, carpet, clothes, guitar strings…
7 Decomposition Reaction A decomposition reaction takes place when a molecule breaks down into two or more substances.The reactant is always a molecule (never a single element).AB A + B
8 Decomposition Reaction An actual example:H2CO3 → H2O + CO2
9 Decomposition Reaction Practical use – car airbagsThe rapid decomposition of sodium azide causes the bag to inflate with nitrogen gas in about seconds!
10 Single Replacement Reaction A single replacement reaction takes place when one element takes the place of another element in a molecule.The reactant side always consists of an element and a molecule.A +BC B + AC
11 Single Replacement Reaction An actual example:2Na + 2H2O → 2NaOH + H2
12 Double Replacement Reaction A double replacement takes place when two molecules exchange elements.There are at least two molecules on both sides of the arrow.AB + CD AD + BC
13 Double Replacement REaction An actual example:CaCO3 + 2HCl → CaCl2 + H2CO3
14 Combustion ReactionA combustion reaction takes place when a hydrocarbon reacts rapidly with oxygen gas.A hydrocarbon is a molecule made of carbon and hydrogen atoms.The products are CO2 and H2O.CH + O CO2 + H2O
15 Combustion ReactionAn actual example:CH4 + 2O2 → CO2 + 2H2O
16 Practical use – internal combustion engine Combustion ReactionPractical use – internal combustion engineMost forms of transportation use this type of engine.