Honors Chemistry
Name: ______________________________________ Date: _______________ Mods: ___________
Ch. 14 – Chemical Kinetics: The Basics
1. Define chemical kinetics –

Examples:
o How quickly will medicine begin working?
o How quickly is the ozone being depleted?
o How long has this fossil been preserved?
2. What will impact the rate of a reaction?

All chemical reactions involve…
o Breaking up reactant bonds
o Forming new product bonds

As a result, the __________________ (identity & state) of the reactants plays a huge role in
reaction rates
14.1
- Factors that Affect Reaction Rates
3. Four Factors that affect reaction rates:

1) Physical State of the Reactants:
o molecules must ________________ in order
to react…
o more collisions = ________________ rate or
reaction
o Solids:
 Ground up solids = faster rate of
reaction
 More _________________
_________ of reactants exposed =
greater likelihood of collisions
o Homogeneous Mixtures:
 gas or liquid solutions react faster
because particles are constantly
colliding with greater kinetic energy
than solids
 for gases, increasing
_______________________ = more
collisions = faster reaction rate

2) Concentration of Reactants:
o ____________________ concentrations have more particles present in solution
 More particles= more collisions = faster reaction rate

3) Temperature:
o ____________________ temperatures = greater kinetic energy
 Faster moving particles = increased # of collisions & with higher energy = faster
reaction
o Example: glowsticks & chemiluminescence (light generated by a chemical change)

4) Presence of a Catalyst:
o Define catalyst –
 .
 Catalyst itself does NOT ________________ (it’s not used up in the actual
chemical reaction)
 Think of catalysts like “matchmakers” bringing reactants together faster
 MnO2 is the catalyst in this reaction (given over the yield arrow)
Cute Video:
http://ed.ted.com/lessons/how-to-speed-up-chemical-reactions-and-get-a-date
14.2 - 14.3 – Reaction Rates & Concentrations
4. Reaction rates can be determined by monitoring the change in _________________________ of
either reactants or products as a function of time.

For the reaction, A  B…
o At the beginning of the reaction (t = 0 sec.), 100% of the particles are reactants
(higher concentration of molecule A)
o Near the end of the reaction, the majority of the particles are products
(higher concentration of molecule B)

For the rxn, C4H9Cl (aq) + H2O (l)  C4H9OH (aq) +
HCl (aq)
o On this reaction, the concentration of the
reactant, C4H9Cl was measured as time
pases
o The rate at which the reaction progresses is
a factor of the concentration or reactant
over time
14.4 – Temperature & Rate
5. The rate of most chemical reactions ___________________ as temperature rises.

Why does temperature have such a significant role in reaction kinetics???
... because of the collision model
6. The Collision Model:

Rxns only occur when reactants collide (reactant bonds are broken & product bonds can form)

Trouble is… any old collision won’t due  … For molecules to react, they must have an
“________________________” collision
o
For “effective” collisions to occur between molecules, there are two requirements:
(1) Molecules collide with each other in the correct ____________________________
(2) Molecules collide with _____________________ _________________ to cause
bond breakage and product formation

The Collision Model: Molecular Orientation
o Molecules interacting are like ___________________
pieces:
o Given, A + B  AB
o Only 1 part of molecule A will react with molecule B to
form an “effective” collision
o If you want to form product AB, A & B must align (or be
oriented) correctly
o Increasing the _____ of collisions = greater chance of
having an effective collision

The Collision Model: Energy
o
Okay… so you have a collision where the molecules are aligned correctly (puzzle
pieces fit)…. But they still might __________ react if they don’t have a high enough
____________________ energy to break pre-existing reactant bonds…
o
So how much energy does it take???
 The amount is different for every reaction, but it is known as the
_______________________ energy (Ea) of the reaction
 Define activation energy (Ea) –
 Analogy:
× In golfing, if the ball
does not have enough
energy, it can’t make
it over a hill to even
get into the hole
×
o
If molecules in a rxn
don’t have enough
energy to get over the
activation energy barrier, the reaction can’t occur to even form products
Energy Diagram & Activation Energy
14.7 – Catalysts
7.
Catalysts

So how does a catalyst speed up a reaction WITHOUT being used up???

Catalysts _____________________ the activation energy required for “effective” collisions
o
8.
This means a ______________________# of collisions will be considered “effective” =
more molecules reacting = faster reaction rate
Catalysts in your body!!!


In Biology, catalysts involved with reactions in
living things are known as
__________________________ (very selective
molecules that specifically target other molecules
– known as “__________________________” –
in the human body)
Enzyme has an activation site which only fits
particular substrates - fit together like a “lock &
key”