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) + N 2 (g) Mg 3 N 2 (s) 3Mg(s) + N 2 (g) Mg 3 N 2 (s)

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

HI H 2 + I 2 2HI H 2 + I 2

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(NO 3 ) 2 (aq) Fe(NO 3 ) 2 (aq) + Pb (s) Cl 2 (aq) + 2NaI (aq) 2NaCl (aq) + I 2 (aq) Ca (s) + 2H 2 O (l) Ca(OH) 2 (aq) + H 2 (g)

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

a. 3NaOH(aq) + Fe(NO 3 ) 3 (aq) Fe(OH) 3 (s) + 3NaNO 3 (aq) b. 3Ba(NO 3 ) 2 (aq) + 2H 3 PO 4 (aq) Ba 3 (PO 4 ) 2 (s) + 6HNO 3 (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.

C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O

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 + N 2  2Li 3 N 6Li + N 2  2Li 3 N a)combination reaction b)decomposition reaction c)single-replacement reaction d)combustion reaction

1. What type of reaction is described by the following equation? 6Li + N 2  2Li 3 N 6Li + N 2  2Li 3 N a)combination reaction b)decomposition reaction c)single-replacement reaction d)combustion reaction

2. Balance the following equation and indicate whether it represents a combustion, combination, or decomposition reaction. H 2 SO 4  H 2 O 2 + SO 2 H 2 SO 4  H 2 O 2 + SO 2 a)H 2 SO 4  H 2 O 2 + SO 2, combination b)H 2 SO 4  H 2 O 2 + SO 2, decomposition c)H 2 SO 4  2H 2 O 2 + SO 2, combination d)H 2 SO 4  2H 2 O 2 + SO 2, decomposition

2. Balance the following equation and indicate whether it represents a combustion, combination, or decomposition reaction. H 2 SO 4  H 2 O 2 + SO 2 H 2 SO 4  H 2 O 2 + SO 2 a)H 2 SO 4  H 2 O 2 + SO 2, combination b)H 2 SO 4  H 2 O 2 + SO 2, decomposition c)H 2 SO 4  2H 2 O 2 + SO 2, combination d)H 2 SO 4  2H 2 O 2 + SO 2, decomposition

3. Predict the missing product in the following unbalanced equation. Pb(NO 3 ) 2 + KOH  KNO 3 + ____________ Pb(NO 3 ) 2 + KOH  KNO 3 + ____________ a)PbOH 2 b)Pb(OH) 4 c)Pb(OH) 2 d)PbOH

3. Predict the missing product in the following unbalanced equation. Pb(NO 3 ) 2 + KOH  KNO 3 + ____________ Pb(NO 3 ) 2 + KOH  KNO 3 + ____________ a)PbOH 2 b)Pb(OH) 4 c)Pb(OH) 2 d)PbOH