Types of Chemical Reactions Chemical reactions are grouped into categories. Within each category, the reactions follow the same pattern Synthesis Reaction Decomposition Reaction Single Displacement Reaction Double Displacement Reaction Combustion Reaction

Synthesis Reactions These reactions involve two or more substances combine to form a larger or more complex substance. General pattern:  A + B  AB element + element  compound compound + compound  one larger compound Example: hydrogen + oxygen  water copper + oxygen  copper oxide calcium oxide + water  calcium hydroxide

Decomposition Reactions These are reactions in which a large or more complex molecule is broken down into two or more simpler substances. General pattern: AB  A + B Example: sodium chloride  sodium + chlorine water  hydrogen + oxygen potassium chlorate  potassium chloride + oxygen

Single Displacement Reactions A reaction in which one element takes the place of another element in a compound, producing a new compound and a new element. General pattern: A + BC  AC + B (if A is a metal) A + BC  BA + C (if A is a non-metal)   A represents an element; BC represents a compound element + compound  compound + element Example:  calcium + hydrogen hydroxide  hydrogen + calcium hydroxide chlorine + sodium bromide  sodium chloride + bromine

Double Displacement Reactions A reaction that occurs when elements in different compounds displace each other or exchange places, producing two new compounds. General pattern: AB + CD  AD + CB   The symbols A, B, C, and D represent atoms, single ions, or polyatomic ions. compound + compound  compound + compound Example: potassium hydroxide + hydrogen chloride  potassium chloride + hydrogen hydroxide lead (II) nitrate + hydrogen chloride  lead (II) chloride + hydrogen nitrate

Sometimes, in a reaction of aqueous reactants, one of the products is insoluble. This product, called a precipitate, appears as a solid in the solution.

Combustion The very rapid reaction of a substance with oxygen to produce compounds called oxides (often called burning)   word equation to represent combustion: fuel + oxygen  oxides + energy The energy produced is mainly in the form of heat and light and the fuel can be a variety of elements and compounds.

Complete Combustion of Hydrocarbons occurs when the supply of oxygen is plentiful the only products of complete combustion are carbon dioxide and water the word equation for the complete combustion of a hydrocarbon is:   hydrocarbon + oxygen  carbon dioxide + water + energy most important fuels we burn are hydrocarbons (Ex: gasoline, natural gas, kerosene)

Incomplete Combustion of Hydrocarbons occurs when oxygen supply is limited products of incomplete combustion are carbon monoxide gas, carbon (soot), carbon dioxide and water carbon monoxide is an odourless, colourless gas that is highly toxic sources of carbon monoxide include: poorly ventilated furnace or a closed garage with a running vehicle in it soot is common in older vehicles with poorly maintained engines

Incomplete Combustion of Hydrocarbons the word equation for incomplete combustion of a hydrocarbon is: hydrocarbon + oxygen  carbon dioxide + water + carbon monoxide + carbon + energy   Some metals react with oxygen in combustion reactions, producing oxides of the metal (e.g., magnesium oxide, MgO) General word equation: element + oxygen  oxide + energy