Types of Chemical Reactions Prentice-Hall Chapter 11.2 Dr. Yager

Objectives Describe the five general types of reactions. Predict the products of the five general types of reactions.

There are five general reaction types: combination decomposition single-replacement double-replacement combustion

A combination (or synthesis) reaction is a chemical change in which two or more substances react to form a single new substance.

Mg(s) + N2(g) Mg3N2(s) 3Mg(s) + N2(g) Mg3N2(s)

A decomposition reaction is a chemical change in which a single compound breaks down into two or more simpler products.

HI H2 + I2 2HI H2 + I2

A single-replacement reaction is a chemical change in which one element replaces a second element in a compound.

The activity series of metals lists metals in order of decreasing reactivity.

Fe(s) + Pb(NO3)2(aq) Fe(NO3)2(aq) + Pb(s) Cl2(aq) + 2NaI(aq) 2NaCl(aq) + I2(aq) Ca(s) + 2H2O(l) Ca(OH)2(aq) + H2(g)

A double-replacement reaction is a chemical change involving an exchange of positive ions between two compounds.

a. 3NaOH(aq) + Fe(NO3)3(aq) Fe(OH)3(s) + 3NaNO3(aq) b. 3Ba(NO3)2(aq) + 2H3PO4(aq) Ba3(PO4)2(s) + 6HNO3(aq)

A combustion reaction is a chemical change in which an element or a compound reacts with oxygen, often producing energy in the form of heat and light.

C6H12O6 + 6O2 6CO2 + 6H2O

How can you predict the products of the five general types of reactions? The number of elements and/or compounds reacting is a good indicator of possible reaction type and thus possible products.

1. What type of reaction is described by the following equation? 6Li + N2  2Li3N combination reaction decomposition reaction single-replacement reaction combustion reaction

1. What type of reaction is described by the following equation? 6Li + N2  2Li3N combination reaction decomposition reaction single-replacement reaction combustion reaction

2. Balance the following equation and indicate whether it represents a combustion, combination, or decomposition reaction. H2SO4  H2O2 + SO2 H2SO4  H2O2 + SO2, combination H2SO4  H2O2 + SO2, decomposition H2SO4  2H2O2 + SO2, combination H2SO4  2H2O2 + SO2, decomposition

2. Balance the following equation and indicate whether it represents a combustion, combination, or decomposition reaction. H2SO4  H2O2 + SO2 H2SO4  H2O2 + SO2, combination H2SO4  H2O2 + SO2, decomposition H2SO4  2H2O2 + SO2, combination H2SO4  2H2O2 + SO2, decomposition

3. Predict the missing product in the following unbalanced equation. Pb(NO3)2 + KOH  KNO3 + ____________ PbOH2 Pb(OH)4 Pb(OH)2 PbOH

3. Predict the missing product in the following unbalanced equation. Pb(NO3)2 + KOH  KNO3 + ____________ PbOH2 Pb(OH)4 Pb(OH)2 PbOH