Unit 11: Classification of Chemical Reactions Cypress Creek HS: Chemistry 1K Chapter 10

Part 2: Classifying and Predicting Reactions

Classifying Chemical Reactions Reactions are classified into several categories. Synthesis A + B  AB Decomposition AB  A + B Single Replacement A + BC  AC + B Double Replacement AB + CD  AD + CB Combustion CxHy + O2  CO2+ H2O By recognizing these patterns, you can classify a reaction and make predictions about its products. Compare these reactions to dancing!

Synthesis Reaction Whenever two or more substances combine to form a single product, the reaction is called a synthesis reaction. When iron rusts, iron metal and oxygen gas combine to form one new substance, iron (III) oxide.

Decomposition Reaction Whenever a compound breaks down into two or more simpler substances, the reaction is called a decomposition reaction. When hydrogen peroxide spontaneously decomposes, it becomes water and oxygen gas. 2H2O2(aq)  2H2O(l) + O2(g)

Single-Displacement Reaction Whenever one element takes the place of another, the reaction is called a single-displacement reaction. This reaction will only occur if the more active metal will become part of a compound in the product. An iron nail soaking in copper (II) sulfate yields iron (II) sulfate and copper

Double-Displacement Reaction Whenever two ionic compounds trade cations, the reaction is called a double-displacement reaction. One of the products will either be water, a gas, or most commonly a precipitate (insoluble in water). Lead (II) nitrate and potassium iodide form lead (II) iodide and potassium nitrate. Note the yellow precipitate is PbI2.

Combustion Reaction Whenever hydrocarbons combine rapidly with oxygen (usually by fire), the reaction is called a combustion reaction. The products will be water and carbon dioxide. Burning methane (CH4) yields water and carbon dioxide This reaction contributes to our greenhouse gases and global warming.

Identifying Chemical Reactions Identify each of the following chemical equations as synthesis, decomposition, single-displacement, double-displacement, or combustion reaction. A) B) C)