Chemical Reactions and Collision Theory Chemistry I 2007
Dec 25, 2015
Chemical reaction Format
Generic Format
A + B C + D
Reactants Products
Substances being mixed
LHS of arrow
Substance being made
RHS of arrow
“Yield” = reaction taking place
Types of Chemical Reactions
5 main types of Chemical Reactions
1) Synthesis
2) Decomposition
3) Single Displacement
4) Double Displacement
5) Combustion
Synthesis
Synthesis means “to make”
Generic RXN
A + B C
Always
makes
1 product
Real Life reaction
Fe
Iron main component in steel
Oxygen
Iron (III) Oxide
AKA RUST
Fe2O3+ O2
DecompositionDecomposing video
Generic Reaction
A B + C
Only 1 Reactant
Real Life Reaction
H2O2 H2 + O2
Hydrogen Peroxide
Single Displacement
Generic Reaction
A + XY X + AY
OR
A + XY Y + XA
Metal for a metal
Non-metal for a Non-metal
Double Displacement
Generic Reaction
AB + XY XB + AY
2 Compounds
(2 or more elements bonded together)
CombustionGeneric reaction
CxHy + O2 CO2 + H2O
ALWAYSHydrocarbon
Burning a substance in the presence of oxygen (O2)
Chemical Reaction Review
Generic Format of reaction
5 different types of chemical reactions
A + B C + D
Reactants Products
A + B C + D
Products
1) Synthesis
2) Decomposition
3) Single Displacement
4) Double Displacement
5) Combustion
How do reactions occur?
Collision Theory Collision TheoryCollision Theory
In order for a chemical reaction to take place, the reactants must collide.
The collision transfers kinetic energy needed to break the necessary bonds so that new bonds can be formed.
Collision requirements
Requirement 1Must have the proper orientation. 2HCl + Mg MgCl2 + H2
H---ClMgWrong Orientation
H-Cl MgH Cl-Mg Correct Orientation
Collision requirements
Requirement 2
Mg
Must have enough kinetic energy to reach a threshold of energy called activation energy
H---Cl H---Cl MgH Cl--Mg
Increasing the Rate of Reactions
What needs to happen in order for the rate of the chemical reaction to increase (go faster)?
More collisions = Faster reaction rate
4 Factors that cause more collisions
1) ____________
2) ____________
3) ____________
4) ____________
5th way in increase Rxn Rate
Add a Catalyst = Speeds up a reaction but is not used in the reaction
Lowers the activation energy
Summary• Molecules must collide with the correct
orientation and enough energy in order to react.
More collisions Faster the reaction rate.
Increase Temperature, Concentration, Pressure, and surface area results in more collisions therefore faster reactions.
Adding a catalysts lowers the energy of activation thus faster reaction rate.