6.1-6.2 Synthesis, decompositon and combustion reactions
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Transcript 6.1-6.2 Synthesis, decompositon and combustion reactions
6.1-6.2 Reaction Types
Synthesis, Decomposition and
Combustion
Types of Chemical Reactions
There are 6 ways elements and
compounds may interact
You can predict the products of a
reaction if you can identify the reactants
you are using
General chemical equations (GCE) use
letters in the place of the symbols of
elements. They help you identify the
reaction type
Symbols in GCE
A single letter is a metal or non-metal Ex. A,
B, X
H is for the hydrogen in an acid
OH is for hydroxide in a base
Two letters Ex. AB, CD represent a compound
Example:
GCE: HB + XOH XB + H2O
Word equation: sulfuric acid + sodium hydroxide sodium sulfate + water
Skeleton equation: H2SO4 (aq) + NaOH (s) Na2SO4 (aq) + H2O (l)
Balanced Equation: H2SO4 (aq) + 2 NaOH (s) Na2SO4 (aq) + 2 H2O (l)
1. Synthesis Reactions
Element + Element Compound
In general A + B AB
Example: Mg (s) + O2 (g) MgO (s)
S8 (g) + O2(g) SO2 (g)
H2 (g) + N2 (g) 2NH3 (g)
2. Decomposition Reactions
A compound is broken down into two or
more elements or simpler compounds
Compound Element + Element
In general, AB A + B
Example: 2 HgO (s) 2 Hg (l) + O2(g)
2 H2O (l) 2 H2 (g) + O2 (g)
3.Combustion Reactions
A compound or element rapidly reacts
with oxygen gas
Heat and light are given off
Usually involve a hydrocarbon (a
compound made up of only hydrogen
and carbon)
The formula for a hydrocarbon is general
CxHy (x and y are subscript numbers)
Ex. CH4 is methane
Combustion
A. Complete combustion
-plenty of oxygen is available
In general, CxHy (g)+ O2 (g) CO2 (g) + H2O (l)
Incomplete combustion
-Oxygen is in limited supply
B.
In general,
CxHy (g)+ O2 (g) C(s) + CO (g) + CO2 (g) + H2O (l)
Impact on the Environment
Global warming – the combustion of
hydrocarbons releases carbon dioxide, a
greenhouse gas
Cleaning oil spills – on land, the oil can
be set on fire (combustion) then the
contaminated soil is removed for
additional treatment
Determine the reaction type
2 Na + Cl2 2 NaCl
Type:
CH4 + 2 O2 CO2 + 2 H2O
Type:
2NI3 N2 + 3 I2
Type:
Predict the Products
1.
2.
3.
NH3
Na + Cl2
S8 + O2
Type:_______
Type:_______
Type:_______
plenty
4.
CH4 + O2
Type:_______
deficient
5.
C 2H 6 + O2
Type:_______
Homework
p. 229 #4-10