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Types of Chemical Reactions. There are millions of compounds, each with the ability to react in different ways In order to predict what reactions will take place, similar reactions are grouped into categories.
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Types of Chemical Reactions • There are millions of compounds, each with the ability to react in different ways • In order to predict what reactions will take place, similar reactions are grouped into categories
Synthesis Reaction: two simple reactants combine to make a larger or more complex product • General Pattern: A + B -> AB • Examples: Zn(s) + S(s) -> ZnS(s) Na(s) + Cl2(g) -> NaCl(s)
Decomposition Reactions: large compounds are broken down into smaller compounds or elements • General Pattern: AB -> A + B • Examples: energy + H2O(l) -> H2(g) + O2(g) energy+ NaN3(s) -> Na(s) + N2(g)
Single Displacement Reactions: one element displaces or replaces an element in a compound • General Pattern: A + BC -> AC + B • Examples: Mg(s)+ CO2(g) -> MgO(s) + C(s) Cu(s) + AgNO3(aq) -> Cu(NO3)2(aq) + Ag(s)
Double Displacement Reactions: two elements in different compounds trade places • General Pattern: AB + CD -> AD + CB • Examples: AgNO3(aq)+ NaCl(aq) -> AgCl(s) + NaNO3(aq) Pb(NO3)2(aq) + KI(aq) -> PbI2(s) + KNO3(aq)
Combustion: reaction in which a fuel “burns” or reacts quickly with oxygen • Most fuels are hydrocarbons (hydrogen + carbon) • The products of hydrocarbon combustion depends on the availability of oxygen • Complete Combustion of Hydrocarbons • Occurs if oxygen is plentiful • Products are carbon dioxide and water hydrocarbon + oxygen -> carbon dioxide + water + energy CxHy+ O2 -> CO2+ H2O + energy
Incomplete Combustion of Hydrocarbons • Occurs if oxygen is limited • Products are carbon dioxide, water, carbon monoxide and carbon (soot) hydrocarbon + oxygen -> carbon dioxide + water + carbon monoxide + carbon + energy CxHy+ O2-> CO2 + H2O + CO + C + energy
Many other substances besides hydrocarbons undergo combustion reactions element + oxygen -> oxide + energy • Corrosion: the breakdown of a metal as a result of chemical reactions with its environment • Read pages 252-254