collision theory

3. A process in which one or more
substance, also called reactants, are
converted to one or more different
substances, known as products.

4. According to this theory, for a chemical reaction
to proceed, there should be an effective collision
between the reactant particles.
For this to occur, two requirements should be
met.
1. Reactants must be in their
proper orientation.
2. Molecules must possess minimum
amount of energy.

5. Proper orientation or alignments of
the reactant particles allows for
effective bond formation during
collision. Particles that are not
properly oriented bounce back
unreacted; hence, no products are
formed.

6.  This figure depicts the possibilities of a reaction between a nitrosyl (NOCl)
molecule and a chlorine atom (Cl) according to the equation: NOCl+Cl
→NO+𝐶𝑙2
 The reactions occur when the free Cl atom directly collides with the Cl atom
of the NOCl molecule. If the Cl atom collides with either the O or N atom,
no reactions occur.

7. The energy that the reactant particles
must possess to initiate the reaction is
referred to as Activation Energy (𝐸𝑎).
This energy can be illustrated using an
analogy. Suppose there is a hump on a
path. For a reaction to occur, reacting
particles must possess enough energy to
jump over the hump.

8. Chemical reactions can be affected by
the following factors:
Temperature
Concentration
Surface area
Catalyst

9. At any given temperature,
some particles travel fast
while others do slowly. If the
temperature of a reaction
system is increased, the
average speed of the reaction
is also increased. This means
that at higher temperature,
the more collisions can
happen between and among
particles with an energy that
is sufficient enough to
surpass the activation
energy of the reaction.

10. Increasing the concentration means increasing the
amount of reacting species per unit volume. This
increases the probability of collision between the
reactant particles because they are closer together.

11.  Do you know that for the same mass of a solid, smaller particles have bigger total
surface area than a large particle?
 The greater the surface area, the greater the frequency of collisions between reacting
particles; hence, the faster reaction.

13. Catalyst is a substance that increases the
rate of a reaction by providing an alternative
pathway for the reaction to occur; that is, one
with a lower activation energy. A catalyst
remains chemically unchanged at the end of
the reaction.

14. Ptyalin in saliva-breaks down starch into dextrin
and maltose
Sucrase in intestinal juice-breaks down sucrose
into glucose and fructose
Lactase in intestinal juice-breaks down lactose into
glucose and galactose
Pepsin in gastric juice- breaks down proteins into
smaller peptides.

15. What is collision theory about?
How does the collision theory explain the
effects of concentration, temperature and
surface area on the rate of a reaction?
How does a catalyst affect the rate of a
reaction?