TYPES OF CHEMICAL REACTIONS – PART A

Dr. Chin ChuRiver Dell Regional High School

CHEMICAL CHANGES (REACTIONS)

2H2 + O2 2H2O

Cu + 2AgNO3 2Ag + Cu(NO

3 )2

NH3 + H

2O NH4OH

2NaOH(aq) + CuCl2(aq) 2NaCl(aq) + Cu(OH)2(s)

How could we get a handle on those

changes?

NH4NO

3(s) N2O(g) + 2H

2O(g)

ORGANIZATION OF CHEMICAL REACTIONS

There got to be some patterns that can be categorized into different

types.

• Chemical reactions are merely rearrangements of atoms into different combinations called compounds.

C + ® OO COOC + O2 CO2

UNIT OBJECTIVES

There are millions of reactions. Can’t remember them all. Fall into several categories. Will learn 5 types. Will be able to predict the products. For some we will be able to predict

whether they will happen at all. Will recognize them by the reactants

EXERCISEBalancing the following chemical equations:

1. aluminum(s) + iodine(s) aluminum iodide(s)

2. sulfur trioxide + water sulfuric acid (H2SO4)

3. lithium oxide + water lithium hydroxide

Do you see the patterns?

SYNTHESIS REACTIONS Called also combination reactions

General Equation: A + B ® AB

Animation: Synthesis Reactions

2 elements, or compounds combine to make one compound.

Mg +O2 ® MgO SO2 + H2O ® H2SO3

TYPES OF SYNTHESIS REACTIONS

Element + element ® compound 2Hg + O2 ® 2HgO 9Mg + 3N2 ® 3Mg3N2

Nonmetalic Oxides + water ® acid SO2 + H2O ® H2SO3 P4O10 + 6H2O ® 4H3PO4

Combination of elements

TYPES OF SYNTHESIS REACTIONSMetalic oxides + water ® base MgO + H2O ® Mg(OH)2 Na2O + H2O ® 2NaOH

Metallic oxides + nonmetallic oxide ® salt MgO + CO2 ® MgCO3 CaO + SiO2 ® CaSiO3

EXERCISE

Do you see the patterns?

1. Thermal decomposition of copper(II) nitrate

Watch the following video clips and write balanced equations:

Video

When heated, solid copper(II) nitrate decomposes into copper(II) oxide, nitrogen dioxide and water vapor.

2. Thermal decomposition of zinc carbonate

When heated, solid zinc carbonate decomposes into solid zinc oxide and carbon dioxide gas.

Video 2

DECOMPOSITION REACTIONS Substances break apart.

General Form: AB ® A + B

Animation: Decomposition

Reactions

Decomposition reactions are reverse of synthesis, with exceptions.

DECOMPOSITION REACTIONSSpecial Cases

Metal Chlorate ® metal chloride + oxygen2KClO3 ®2KCl + 3O2

Metal bicarbonate ® metal oxide + carbon dioxide + water2NaHCO3 ® Na2O + 2CO2 + H2O

DECOMPOSITION REACTIONS

Most oxides are stable, only few decompose:

2HgO ® Hg + O2Electrolysis of molten salt

(decomposition by electricity) is the only means for decomposition for some substances:2H2O ® 2H2 + O2

2NaCl ® 2Na + Cl2

Special Cases

DEMOS

Do you see the patterns?

1. The methane bubble

2. The perfect combution (ethanol) http://www.youtube.com/watch?v=Lb-KB_BshUc&NR=1

3. Burning of methanol

COMBUSTION REACTIONS

A compound composed of only C, H and maybe O is reacted with oxygen

If the combustion is complete, the products will be CO2 and H2O.

If the combustion is incomplete, the products will be CO and H2O.

EXERCISESC4H10 + O2 ® (complete combustion)

C4H10 + O2 ® (incomplete combustion)

C6H12O6 + O2 ® (complete combustion)

C8H8 +O2 ® (incomplete combustion)

MORE EXERCISES Write a balanced equation for the complete

combustion of each of these compounds.a) acetic acid, HC2H3O2 c) glycerol, C3H8O3

b) decane, C10H22 d) sucrose, C12H22O11

Write a balanced equation for the incomplete combustion of each of these compounds.a) glycerol, C3H8O3 c) acetic acid, HC2H3O2

b) glucose, C6H12O6 d) acetylene, C2H2