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Types of Chemical Reactions of Metals

A chemical reaction is a process by which one type of chemical substance is converted to another type of chemical substance. All chemical reactions are characterized by a change in energy. Reactions either release or absorb energy from their surroundings as they proceed. In metals, there are four types of chemical reactions: synthesis reactions, decomposition reactions, single displacement reactions and combustion reactions.

  1. Synthesis Reaction

    • When two elements combine to form a compound, it is called a synthesis reaction. Basically, two reactants combine to form a product. Types of synthesis reaction include: combining a metal and a nonmetal to form a compound; reaction between a metallic oxide and water to form a hydroxide; and a metal reacting with oxygen to form metal oxide. Examples include sodium reacting with chlorine to form sodium chloride and aluminum reacting with fluorine to form aluminum fluoride.

    Decomposition Reaction

    • When a compound breaks into its elements or into simpler compounds, it is called a decomposition reaction. In this reaction, a reactant breaks into two or more products. Types of decomposition reaction include: metallic carbonates, when heated, produce metallic oxide and carbon dioxide (e.g., decomposition of calcium carbonate to calcium oxide and carbon dioxide); metallic chlorides break into a metallic element and chlorine (e.g., decomposition of sodium chloride to sodium and chlorine); and metallic chlorates break into metallic chlorides and oxygen (e.g., decomposition of potassium chlorate to potassium chloride and oxygen).

    Single Replacement Reaction

    • A single replacement reaction takes place when one element replaces another in a compound. The types of single replacement reaction include: replacement of a metal in a compound by a more active metal (e.g., iron reacting with copper sulfate to form iron sulfate and copper); replacement of hydrogen in water by an active metal (e.g., sodium reacting with water to form sodium hydroxide and hydrogen); replacement of hydrogen in acids by an active metal (e.g., zinc reacting with hydrochloric acid to form zinc chloride and hydrogen); and replacement of nonmetals by more active metals (e.g., zinc reacting with sodium bromide to form sodium chloride and bromine).

    Double Replacement Reaction

    • When a metal replaces a metal in a compound, it is called a double replacement is reaction. The types of double replacement reactions include formation of a precipitate, formation of a gas and formation of water. Examples include: sodium chloride reacting with silver nitrate to form sodium nitrate and silver chloride; hydrochloric acid reacting with ferric sulfide to form ferrous chloride and hydrogen sulfide; and hydrochloric acid reacting with sodium hydroxide to form sodium chloride and water.

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