Chemical Reactions PPT
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Transcript of Chemical Reactions PPT
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CHEMICAL REACTION
A process in which one or more
substances are changed into others.
Chemical reactions tend to involve themotion of electrons, leading to the
formation and breaking of chemical
bonds.
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MEANING OF A CHEMICAL
REACTION
Products - product is the result of a chemical
reaction.
Reactants - reactants are the elements or
the compounds that enter a chemicalreaction.
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TYPES OF REACTIONS
EXOTHERMIC
ENDOTHERMIC
SYNTHESIS DECOMPOSITION
SINGLEDISPLACEMENT
DOUBLED
ISPL
ACE
MENT
COMBUSTION
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EXOTHERMIC
Many chemical reactions release energy
in the form of heat, light, or sound.
Exothermic reactions produce heat and
can even be explosive.
Na + 0.5Cl2 = NaCl
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ENDOTHERMIC
Endothermic reactions cannot occur
spontaneously and absorb energy. .
Work must be done in order to get these
reactions to occur. When endothermic
reactions absorb energy, a temperature
drop is measured during the reaction.
sunlight + 6CO2(g) + H2O(l) =
C6H12O6(aq) + 6O2(g)
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SYNTHESIS
In a synthesis reaction two or morechemical species combine to form a
more complex product.
A + BAB
8 Fe + S8 8 FeS
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DECOMPOSITION
In a decomposition reaction a compound
is broken into smaller chemical species.
ABA + B
2 H2
O 2 H2
+ O2
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SINGLE DISPLACEMENT
A substitution or single displacementreaction is characterized by one element
being displaced from a compound by
another element.
A + BC AC + B
Zn + 2 HClZnCl2 + H2
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DOUBLE DISPLACEMENT
In a double displacement or metathesis
reaction two compounds exchange bonds or
ions in order to form different compounds.
AB + CDAD + CB
NaCl+ AgNO3 NaNO3 + AgCl
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COMBUSTION
A reaction that involve the presence ofoxygen and releases energy. Usually ina combustion reaction oxygen combines
with another compound to form carbondioxide and water.
ACXHY + ((2AX +AY/2)/2)O2 (AX)CO2 +(AY/2)H2O
C10H8 + 12 O2 10 CO2 + 4 H2O
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MASS LAW
The law of conservation of mass states
that matter can neither be created nor
destroyed. The mass of the reactants
must ALWAYS equal the mass of the
products.
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PURPOSE OF BALANCING
REACTIONS
The equation has to be equal because
matter can neither be created nor
destroyed, but it can be transferred,
which is what happens in chemical
reactions. The amount you start with on
the left has to be the same amount you
end up with on the right.
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EXAMPLES OF BALANCING THE
AFOREMENTIONED REACTION
TYPES
3H2 + N2 2 NH3
2C2H6 + 7O2 4CO2 + 6H2O
4Al +3O2 2Al2O3
2 Al + 3 CuO Al2O3 + 3 Cu
I2 + 2 Na2S2O3 2 NaI + Na2S4O6
K2O + H2O 2 KOH
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EXAMPLES OF BALANCING THE
AFOREMENTIONED REACTION
TYPES
Fe2(SO4)3 + 12 KSCN 2 K3Fe(SCN)6 + 3
K2SO4
(NH4)2CO3 2 NH3 + CO2 + H2O
2 H2 + O2 2 H2O
6 Mg + P4 2 Mg3P2 CaCl2 + 2 AgNO3 2 AgCl + Ca(NO3)2