Chapter 8 Chemical Reactions 8.3 Types of Reactions Learning Goal Identify a reaction as a combination, decomposition, single replacement, double replacement, or combustion. In a combination reaction, two or more substances combine to form one substance as the product. © 2014 Pearson Education, Inc.

Types of Reactions Chemical reactions may be classified as combination decomposition single replacement double replacement combustion

Combination Reactions In a combination reaction, two or more elements form one product two or more simple compounds combine to form one product 2Mg(s) + O2(g)  2MgO(s) N2(g) + 3H2(g)  NH3 (g)

Combination Reactions In a combination reaction, two or more substances combine to form one substance as the product.

Decomposition Reactions In a decomposition reaction, one reactant splits into two or more simpler substances

Decomposition Reactions In a decomposition reaction, one reactant breaks down into two or more products.

Chemistry Link to Health Photochemical smog is prevalent in cities that depend on cars for transportation is formed when nitrogen oxide (NO) emissions from cars combine with oxygen gas to form nitrogen dioxide 2NO(g) + O2(g)  2NO2(g)

Chemistry Link to Health Nitrogen dioxide (NO2) gas is a reddish-brown gas that irritates eyes and is damaging to lungs reacts in the presence of sunlight to form NO molecules and O atoms NO2(g)  NO(g) + O(g) oxygen atoms

Chemistry Link to Health The reddish-brown color of smog is due to nitrogen dioxide.

Chemistry Link to Health Single oxygen atoms are very reactive and combine with molecules in the atmosphere to form ozone. O(g) + O2(g)  O3(g) Ozone In the lower atmosphere, ozone irritates the eyes and respiratory tract damages fabric and rubber as well as trees and crops

Single-Replacement Reactions In a single-replacement reaction, an uncombined element replaces an element in a compound. Zn(s) + 2HCl(aq)  ZnCl2(aq) + H2(g) Fe(s) + CuSO4(aq)  FeSO4(aq) + Cu(s)

Single-Replacement Reactions In a single replacement reaction, an atom or ion replaces an atom or ion in a compound.

Double-Replacement Reactions In a double-replacement reaction, two elements in the reactants exchange places. AgNO3(aq) + NaCl(aq)  AgCl(s) + NaNO3(aq) NaOH(aq) + HCl(aq)  NaCl(aq) + HOH(l)

Double-Replacement Reactions In a double replacement reaction, the positive ions in the reactants replace each other.

Combustion Reactions In a combustion reaction, carbon containing compounds, fuel burns in oxygen from the air to produce carbon dioxide, CO2, water, H2O, and heat or flame.

Combustion Reactions Butane, an alkane with 4 C atoms and 10 H atoms, is used as a fuel for a camp stove.

Summary of Reaction Types

Learning Check Identify each type of reaction as (C) combination (D) decomposition (SR) single replacement (DR) double replacement 3Ba(s) + N2(g)  Ba3N2(s) 2Ag(s) + H2S(aq)  Ag2S(s) + H2(g) SiO2(s) + 4HF(aq)  SiF4(s) + 2H2O(l) K2CO3(s)  K2O(aq) + CO2(g)

Solution Identify each type of reaction as (C) combination (D) decomposition (SR) single replacement (DR) double replacement C 3Ba(s) + N2(g)  Ba3N2(s) SR 2Ag(s) + H2S(aq)  Ag2S(s) + H2(g) DR SiO2(s) + 4HF(aq)  SiF4(s) + 2H2O(l) D K2CO3(s)  K2O(aq) + CO2(g)