Types of Chemical Reactions

8-2

Beaker Breaker

• Balance the following equation:

• ______H3PO4 _______H4P2O7 + ______H2O

Beaker Breaker

• Predict the reaction that might occur when aluminum reacts with hydrochloric acid.

• Write a balanced equation for this reaction.

5 types of chemical reactions:

1. synthesis (composition)

2. decomposition

3. single-replacement (displacement)

4. double-replacement (displacement)

5. combustion

Synthesis Reactions

• 2 or more substances combine to form a new compound

• 2 H2 + O2 2H2O

Decomposition

• a single cmpd undergoes a rxn that produces 2 or more simpler substances

•H2CO3 H2O + CO2

Decomposition of…

• binary cmpds

• metal carbonates

• metal hydroxide

• metal chlorates

• acid

Single Replacement Reaction

• one element replaces a similar element in a cmpd

• 2 Al + Fe2O3 Al2O3 + 2 Fe

Single Replacement Reaction of…

• a metal in a cmpd by another metal

• hydrogen in water by a metal

• hydrogen in an acid by a metal

• replacement of halogens

Double replacement reactions

• ions of 2 cmpds exchange places in an aqueous solution to form 2 new cmpds

• ZnBr2 + 2 AgNO3 Zn(NO3)2 + 2 AgBr

Double displacement reactions…..

• formation of a precipitate

• formation of a gas

• formation of water

Combustion Reactions

• substance reacts with oxygen and releases a large amount of energy (light and heat)

• hydrogen + oxygen water vapor

• hydrocarbon + oxygen carbon dioxide + water

• Combustion (burning) of propane:

• C3H8(g) + O2

C3H8(g) + 5O2(g)

3CO2(g) + 4H2O(g)

Practice

• Complete #2 on page 264

#2 page 264

a. Synthesis

b. Single-replacement (single-displacement)

c. Decomposition

d. Combustion

e. Decomposition

f. Synthesis

g. Double-replacement (double-displacement)

Beaker Breaker

• Identify the following reactions as either synthesis, decomposition, single replacement, double replacement, or combustion:

2C2H6 + 7O2 4CO2 + 6H2O

Ca + 2HCl CaCl2 + H2

Beaker Breaker Cont.

• Write a paragraph explaining why the formation of water can be classified as a synthesis or combustion.

In Depth Look atTypes of Chemical

Reactions

• synthesis (composition)

• decomposition

• single-replacement (displacement)

• double-replacement (displacement)

Synthesis Reactions

• 2 or more substances combine to form a new compound

• 2 H2 + O2 2H2O

Reactions of metals with oxygen and sulfur

• magnesium metal + oxygen

• barium + sulfur (S8)

2Mg(s) + O2(g) 2 MgO(s

8Ba(s) + S8(s) 8BaS(s)

Some metals can form oxides of varying oxidation #:

• iron + oxygen iron(II) oxide

• iron + oxygen iron(III) oxide

Some metals can form oxides of varying oxidation #:

• iron + oxygen iron(II) oxide

• 2Fe(s) + O2(g) 2FeO(s)

• iron + oxygen iron(III) oxide

• 4Fe(s) + 3O2(g) 2Fe2O 3(s)

Nonmetals can also form oxides

• S8(s) + 8O2(g) 8SO2(g)

• C(s) + O2(g) CO2(g)

• 2C(s) + O2(g) 2CO(g)

Reactions of metals with halogens• potassium + iodine

• strontium + bromine

• cobalt + fluorine [cobalt(III) ion forms]

Reactions of metals with halogens• potassium + iodine • 2K(s) + I2(g) 2KI(s)

• strontium + bromine • Sr(s) + Br2(l) SrBr2(s)

• cobalt + fluorine [cobalt(III) ion forms]

• 2Co(s) + 3F2(g) 2CoF3(s)

Synthesis reactions with metal oxides

• active metals* oxides + water hydroxides

• calcium oxide + water

• *(see p. 266)

CaO(s) + H2O(l) Ca(OH)2(s)

Synthesis reactions with nonmetal oxides

• nonmetal oxides + water oxyacids

• sulfur dioxide + water

SO2(g) + H2O(l) H2SO3

• when SO2 reacts with rain water to form H2SO3, it can further react with the atmosphere….

• H2SO3 + O2 2 H2SO4

Synthesis reaction of metal oxide & nonmetal oxide

• calcium oxide + sulfur dioxide

CaO(s) + SO2(g) CaSO3(s)

Beaker Breaker

• Identify the following reactions as either synthesis, decomposition, single replacement, double replacement, or combustion:

K + Cl2 KCl

CH4 + O2 CO2 + H2O

Fe + HCl FeCl3 + H2

Decomposition

• a single cmpd undergoes a rxn that produces 2 or more simpler substances

•H2CO3 H2O + CO2

Decomposition of…

• binary cmpds

• metal carbonates

• metal hydroxide

• metal chlorates

• acid

Decomposition of binary cmpds

• simplest decomposition rxn

• decomposition into elements

• ELECTROLYSIS: decomp by an electric current

• 2 H2O(l) electricity--->

• 2 H2O(l) electricity---> 2H2(g) + O2(g)

Decomposition of Metal Carbonates

• when heated (∆), produce a metal oxide and carbon dioxide gas

• CaCO3(s) -∆

• CaCO3(s) -∆ CaO(s) + CO2(g)

Decomposition of Metal Hydroxides

• all metals except Gp 1 decomp when heated to produce metal oxides and water

• Ca(OH)2(s) -∆ CaO(s) + H2O(g)

• Ca(OH)2(s) -∆ CaO(s) + H2O(g)

Decomposition of Metal Chlorates

• when heated, decompose to produce a metal chloride and oxygen

• 2KClO3(s) -∆ 2KCl(s) + 3O2(g)

• 2KClO3(s) -∆ 2KCl(s) + 3O2(g)

Decomposition of Acids

• Many acids decompose into nonmetal oxides and water

• H2SO4(aq) -∆

• H2CO3(aq)

• H2SO4(aq) -∆ SO3(g) + H2O(l)

• H2CO3(aq) CO2(g) + H2O(l)

Single Replacement Reaction

• one element replaces a similar element in a cmpd

• 2 Al + Fe2O3 Al2O3 + 2 Fe

Single Replacement Reaction of…

• a metal in a cmpd by another metal

• hydrogen in water by a metal

• hydrogen in an acid by a metal

• replacement of halogens

Replacement of a metal in a cmpd by another metal

• aluminum + lead(II) nitrate

• (p. 266 Al is more reactive than Pb so a spontaneous reaction will occur)

2Al(s)+ 3 Pb(NO3)2(aq)

3 Pb(s) + 2Al(NO3)3(aq)

Replacement of H in water by a metal (active)

• very active metals (i.e. Gp 1) pulls one H from the water

• sodium + water

2Na(s) + 2H2O(l)

2NaOH(aq) + H2(g)

Replacement of H in water by a metal (less-active)

• less- active metals reacts with steam and pulls-off both hydrogens from the water

• iron + water

3Fe(s) + 4H2O(g)

Fe3O4(s) + 4H2(g)

Replacement of H in an acid by a metal

• more-active metals reacts with some acidic soln’s

• magnesium + hydrochloric acid

Mg(s) + 2 HCl(aq)

H2(g) + MgCl2(aq)

Replacement of Halogens

• a more reactive halogen will replace a

less-active halogen

• the higher up in the Gp 17 family, the MORE reactive the halogen

• Reactivity: F>Cl>Br>I

• chlorine gas + potassium bromide sol’n

Cl2(g) + 2KBr(aq) 2KCl(aq) + Br2(l)

• fluorine gas + sodium chloride sol’n

• bromine liquid + potassium chloride sol’n

• fluorine gas + sodium chloride sol’n • F2(g) + 2NaCl(aq) 2NaF(aq) + Cl2(g)

• bromine liquid + potassium chloride sol’n

• Br2(l) + KCl(aq) no reaction (NR)

Double replacement reactions

• ions of 2 cmpds exchange places in an aqueous solution to form 2 new cmpds

• ZnBr2 + 2 AgNO3 Zn(NO3)2 + 2 AgBr

Double displacement reactions…..

• formation of a precipitate

• formation of a gas

• formation of water

Formation of a precipitate

• one product is insoluble (or just slightly soluble) …see page 427

• potassium iodide + lead (II) nitrate

2KI(aq) + Pb(NO3)2(aq)

PbI2(s) + 2KNO3(aq)

Formation of a gas

• one product is an insoluble gas and bubbles out

• iron(II) sulfide + hydrochloric acid sol’n

FeS(s) + 2HCl(aq)

H2S(g) + FeCl2(aq)

Beaker Breaker

• Complete and balance each of the following reactions, and then identify each by type.

1. Calcium + sodium nitrate ________

2. Silver nitrate + potassium iodide _____

Formation of Water

• one of the products yields the molecular cmpd water

• hydrochloric acid + sodium hydroxide

HCl(aq) + NaOH(aq)

NaCl(aq) + H2O(l)