Transcript PowerPoint - Types of Chemical Reactions

Chemical Reactions
Types of Reactions
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

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Synthesis reactions
Decomposition reactions
Single displacement reactions
Double displacement reactions
CO…….
Types of Reactions
Combustion reactions
decomposition reactions
precipitation reactions
neutralization reactions
o acid
o base
 oxidation-reduction reaction
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You need to be able to identify each type.
1. Synthesis
Example C + O2
C + O O
H2 +1/2O2
General:

O C O
H2O
A + B  AB
Ex. Synthesis Reaction
EXPLOSIVE
??????
Practice
• Predict the products.
Na(s) + Cl2(g) 
NaCl(s)
Mg(s) + F2(g)  MgF2(s)
Al(s) + F2(g) 
•
AlF3(s)
Now, balance them. ?
SOLUTION
2 Na(s) + Cl2(g)  2 NaCl(s)
Mg(s) + F2(g)  MgF2(s)
2 Al(s) + 3 F2(g)  2 AlF3(s)
2. Decomposition
Example: NaCl
Cl
Na
1/2
Cl 2 +
Na
General: AB  A + B
Ex. Decomposition Reaction
3. Single Displacement
Example: Zn + CuCl2
Zn was oxidized
Went from neutral (0) to (+II )
Cu
Cl
+
Cl
Zn

Zn
Cl
+
Cu
Cl
Cu was reduced
Went from (+II) to Neutral (0)
General: AB + C  AC + B
Ex. Single Replacement Reaction
Single Replacement Reactions
• Write and balance the following single replacement
reaction equation:
• Zn(s) + 2 HCl(aq)  ZnCl2 + H2(g)
• 2 NaCl(s) + F2(g)  2 NaF(s) + Cl2(g)
•2 Al(s)+ 3 Cu(NO3)2(aq)
3 Cu(s)+ 2 Al(NO3)3(aq)
4. Double displacement
Example: MgO + CaS
Mg
O
+
Ca
S

Mg
S
+
Ca
O
General: AB + CD  AD + CB
Double Replacement Reactions
• Think about it like “foil”ing in algebra, first and last ions go
together + inside ions go together
• Example:
AgNO3(aq) + NaCl(s)  AgCl(s) + NaNO3(aq)
• Another example:
K2SO4(aq) + Ba(NO3)2(aq)  KNO3(aq)2+ BaSO4(s)
Practice
•
Predict the products.
1.
2.
3.
4.
5.
HCl(aq) + AgNO3(aq) 
CaCl2(aq) + Na3PO4(aq) 
Pb(NO3)2(aq) + BaCl2(aq) 
FeCl3(aq) + NaOH(aq) 
H2SO4(aq) + NaOH(aq) 
6.
KOH(aq) + CuSO4(aq) 
5. Combustion Reactions
a. Combustion reactions
hydrocarbon reacts with oxygen gas.
• This is also called burning!!!
In order to burn something you
need the 3 things in the “fire
triangle”:
1) Fuel (hydrocarbon)
2) Oxygen
3) Something to ignite the reaction
(spark)
Combustion Reactions
In general:
CxHy + O2  CO2 + H2O + heat
Products are ALWAYS
carbon dioxide and water. (although
incomplete burning does cause some byproducts like carbon monoxide)
Combustion is used to heat homes and run
automobiles (octane, as in gasoline, is
C8H18)
Combustion
Example
C5H12 + 8 O2  5 CO2 + 6 H2O
H.W:.
Write the products and balance the following
combustion reaction:
C10H22 + O2  ?????
Precipitation Reactions
The process of separating a substance from
a solution as a solid.
AgNO3 + NaCl ---> AgCl + NaNO3
precipitate
Neutralization Reactions
• acid
• base
• salt
Household acids and Bases
Neutralization Reactions
• Acid
Any of a large class of sour-tasting substances whose
aqueous solutions are capable of turning blue litmus
indicators red, of reacting with and dissolving certain
metals to form salts, and of reacting with bases or
alkalis to form salts.
Substance that donates H+ ions to solution
Neutralization Reactions
• Base
Any of a large class of compounds, including
the hydroxides and oxides of metals, having a
bitter taste, a slippery solution, the ability to
turn litmus blue, and the ability to react with
acids to form salts.
Substance that donates a OH-1 ion to solution
Neutralization Reactions
• salt
 The term salt is also applied to substances
produced by the reaction of an acid with a
base, known as a neutralization reaction.
 Salts are characterized by ionic bonds,
relatively high melting points, electrical
conductivity when melted or when in solution,
and a crystalline structure when in the solid
state.
Neutralization Reactions
acid + base ---> “salt” + water
Neutralization Reactions
acid + base ---> “salt” + water
HCl + NaOH ---> NaCl + H2O
Neutralization Reactions
acid + base ---> “salt” + water
H2SO4 + 2KOH ---> K2SO4 + 2H2O
Strong vs. Weak Acids and Bases
strong - completely ionized
weak - partially ionized
Oxidation-Reduction Reaction
Oxidation - loss of electrons
Reduction - gain of electrons
Redox reaction
oxidizing agent - substance that causes oxidation
reducing agent - substance that cause reduction
Decomposition Reactions
Separation into constituents by chemical reaction.
Homogenous Equilibrium
Consider colorless frozen N2O4. At room
temperature, it decomposes to brown NO2:
N2O4(g)
2NO2(g).
At some time, the color stops changing
and we have a mixture of N2O4 and NO2.
Chemical equilibrium is the point at which
the concentrations of all species are
constant.
The Equilibrium Constant
For a general reaction in the gas phase
aA + bB ═ cC+ dD
the equilibrium constant expression is
Keq = pcC pdD
paA pbB
where Keq is the equilibrium constant.
The Equilibrium Constant
For a general reaction
aA +Bb ═ cC + dD
the equilibrium constant expression
everything in solution is
Keq= [C]c[D]d
[A]a[B]b
where Keq is the equilibrium constant.
for
Homogenous Equilibrium
At equilibrium, as much N2O4 reacts to form NO2 as
NO2 reacts to re-form N2O4:
The double arrow implies the process is dynamic.
Consider
Forward reaction: A  B Rate = kf [A]
Reverse reaction: B  A Rate = kr [B]
At equilibrium kf [A] = kr [B].
The End