types of chemical reactions let’s classify.... why classify chemical reactions? “i wonder what...
TRANSCRIPT
Types of Chemical Reactions
let’s classify . . .
Why Classify Chemical Reactions?
“I wonder what will happen if I light a match in a room full of gasoline vapour?”
What type of reaction do you think will occur?Combustion—exothermic and rapid!
How do you know this?
Five Types of Chemical Reactions
1. Synthesis2. Decomposition3. Combustion4. Single Displacement5. Double Displacement
let’s look more closely at each type . . .
Synthesis Reactions
Occur when two or more elements or compounds combine to form a new substance. These reactions come in the general form of:
A + B AB
eg. 8 Fe + S8 8 FeS
Predict the products . . .
Na(s) + Cl2(g)
NaCl(s)Al(s) + Br2(l)
AlBr3(s)
Fe(s) + Cl2(g)
FeCl3(s)
Mg(s) + O2(g)
MgO(s)
Sb(s) + Cl2(g)
SbCl3(s)
P4(s) + O2(g) P4O10(s)
P4O10(s) + HOH(l) H3PO4(aq)
CaO + HOH(l) Ca(OH)2(aq)
Reactions of Oxides with Water
a) Metal oxide + HOH basic solutioneg. Na2O(s) + HOH(l)
NaOH(aq)
b) Non-metallic oxide + HOH acidic solution
eg. SO3(g) + HOH(l)
H2SO4(aq)
Write the product(s) of each of the following synthesis reactions
Zn(s) + S8(s)
ZnS(s)Zn(s) + O2(g)
ZnO(s)S8(s) + O2(g)
SO2(g)
Synthesis reactions and Acid Precipitation
CO2(g) + H2O(l)
H2CO3(aq)
S8(s) + O2(g) (unbalanced)
SO2(g)
SO2(g) + O2 (unbalanced)
SO3(g)
SO3(g) + H2O(l) (unbalanced)
H2SO4(aq)
Decomposition Reactions
A compound decomposes—or breaks down into its elements or into other compounds.
C A + B
A decomp. reaction is the opposite of asynthesis reaction.
Types of Decomposition Rxns
• binary cmpd its elements
• metal nitrate metal nitrite + O2
• metal carbonate metal oxide + CO2
• metal hydroxide metal oxide + H2O
Examples
NaCl(s) Na(s) + Cl2(g)
KNO3(s)
KNO2(s) + O2
Na2CO3
Na2O + CO2
NaOH Na2O + H2O
Examples of decomposition reactions
2 HOH(l) 2 H2(g) + O2(g)
NH4NO3(s) N2O(g) + 2 HOH(g)
H2O2(aq) (with MnO2(s) catalyst) HOH(l) + O2(g)
What’s a catalyst?
A catalyst increases the rate of a chemical reaction . . . but
is not used up in the reaction.A catalyst is present at the beginning and at the
end of a chemical reaction.eg. catalytic converter in an automobile’s
exhaust system
More examples of decomp rxns (with video clips)
KClO3(s) + heat
KCl(s) + O2(g)
http://www.youtube.com/watch?v=7Xu2YZzufTM
(NH4)2Cr2O7(s) + heat
Cr2O3(s) + N2(g) +
HOH(g)http://www.youtube.com/watch?v=6mJbcMOa0GA
Are the products of a decomposition reaction stable or unstable compounds?
What product(s) have you noticed so far?
N2, HOH, KCl, etc
These are allstable compounds.
Q: What is Beethoven doing in his grave?
A: Decomposing
Combustion Reactions
Used for cooking, heat, transportation and more.
Complete combustion of a C & H (& O) containing fuel in the presence of sufficient O2 yields
CO2 and HOHIncomplete combustion yieldsC(s) + CO(g) + CO2(g) + H2O(g)
examples of combustion of C&H(&O) - containing fuels
CH3CH2OH(l) + O2(g) (sufficient O2)
CO2(g) + HOH(g)
C8H18(l) + O2(g) incomplete combustion
C(s) + CO(g) + CO2(g) + HOH(g)
(Incomplete combustion—not enough O2 present)
Is it possible to balance this equation?
Here’s an example of just how combustible methane is:
Here’s what happened when we put a balloon full of H2 and O2 on top of a sheet of Al foil in a microwave oven.
rxn is:2 H2(g) + O2(g) 2 H2O(g) + energy
Can also have combustion of elements other than carbon
eg. Mg(s) + O2(g) MgO(s)
H2(g) + O2(g) HOH(g)
How else could we classify these reactions?synthesis
Check out this video
http://www.stumbleupon.com/su/4nU70a/current.com/entertainment/comedy/90267537_chemical-party.htm