Factors Affecting the Rate of Chemical Reaction Flashcards
(17 cards)
is the speed at which the reaction
occurs (i.e. speed at which the reactants are used or products are
produced).
Rates of Reaction
may be used to explain
how the various factors will affect the rate of a chemical reaction.
KINETIC MOLECULAR THEORY
Collisions that result in the formation of products are called
EFFECTIVE COLLISIONS
The idea of effective collisions is called the
COLLISION MODEL
the rate of a reaction may be
increased by increasing the number of total collisions or by
increasing the number of effective collisions by decreasing the
activation energy.
Collision Mode
The greater the number of particles the greater the number of total
collisions. Since the total number of collisions has increased the
number of effective will also increase therefore the rate of the
reaction will increase.
Concentration (Pressure of Gases)
If the size of a solid particle is decreased, there will be more surface area available for collisions to occur.
Surface Area (Size of Solid Particles)
The temperature of a substance is a measure of the average kinetic
energy of the particles. The higher the temperature, the faster the
particles are moving which will increase the chance for collisions.
Temperature of Reactants
Reactions where all reactants are in the same state (homogeneous
reactions) will occur at a faster rate than reactions where reactants
are in different states (heterogeneous). This is because the reactants will have a greater opportunity of colliding. The state of the reactants will also affect the rate.
The relative rates are:
Gases → fastest
Liquids/ Solutions → fast
Solids → slow
State or Phase of the Reactants
The type of reactants will determine the activation energy needed to
break bonds and form the intermediate state called the
ACTIVATED COMPLEX
Nature of Reactants
works by providing an alternative pathway for the reaction which
has a lower activation energy. Lowering the activation energy will only increase the number of effective collisions. The number of total collisions will not be affected.
Presence of a Catalyst
Summary
Increasing the temperature,
concentration, and surface area
of reactants generally increases
the rate of reaction.
How does increasing the
temperature affect the rate of
a chemical reaction?
a. It decreases the rate of reaction
b. It has no effect on the rate of
reaction
c. It increases the rate of reaction
d.It can either increase or decrease
the rate of reaction, depending on
the reaction
c. It increases the rate of reaction
What is the effect of increasing the
concentration of reactants on the rate of reaction?
a. It has no effect on the rate of reaction
b. It increases the rate of reaction
c. It decreases the rate of reaction
d. It can either increase or decrease the rate
of reaction, depending on the reaction
b. It increases the rate of reaction
How does increasing the surface area of a solid reactant affect the rate of reaction?
a. It has no effect on the rate of reaction
b. It decreases the rate of reaction
c. It increases the rate of reaction
d. It can either increase or decrease the rate of reaction, depending on the reaction
c. It increases the rate of reaction
Why does the rate of a chemical reaction increase with a rise in the temperature of the reactants?
a. Heat decreases the surface area of particles available for collision.
b. Heat makes the particles of the reactants move more rapidly, which enhances the possibility of collisions.
c. Heat increases the concentration of the reactants by evaporating some of them.
d. Heat makes the molecules react more frequently by increasing their size.
b. Heat makes the particles of the reactants move more rapidly, which enhances the possibility of collisions.
Which of the following will hasten the rate of reaction?
a. Adding a negative catalyst.
b. Maintaining the temperature constant.
c. Decreasing the amount of reactants.
d. Grinding the reactants
d. Grinding the reactants
