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TYPES OF CHEMICAL REACTIONS – PART A
Dr. Chin Chu
River Dell Regional High School
CHEMICAL CHANGES (REACTIONS)
2H2 + O2 2H2O
Cu +
2AgN
O3 2A
g + C
u(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 COO
C + 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
EXERCISE
Balancing 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 REACTIONS
Metalic 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 REACTIONS
Special Cases
Metal Chlorate ® metal chloride + oxygen
2KClO3 ®2KCl + 3O2
Metal bicarbonate ® metal oxide + carbon dioxide + water
2NaHCO3 ® Na2O + 2CO2 + H2O
DECOMPOSITION REACTIONS
Most oxides are stable, only few decompose:
2HgO ® Hg + O2
Electrolysis 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.
EXERCISES
C4H10 + 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