We can find out the rate of the
chemical reaction by following the
amount of reactants used over some
time.
RoR= Amount of reactant used/ time
We can also found out the rate of
a chemical reaction by following
the amount of products being
made over time.
RoR=Amount of product formed/ time
The slope of any line of the
graph at any given time
tells us the rate of the
reaction. The steeped the
slope, the faster the
reaction.
C8.2 Collision theory and surface area.
Main Factors that affect rates of reaction
Temperature
Surface Area
Concentration
of solutions or
pressure of gas.
presence of catalyst
Collision Theory
Particles must collide with
each other with a certain
minimum amount of energy
before they can react.
Activation energy
The minimum
amount of energy
that particles must
have before they
can react
The rate of a chemical reaction increases
if the surface area of any solid reactant
increases. This increases the frequency of
collisions between reacting particles.
C8.3 The effect of temperature.
As temperature increases, the rate of reaction increase too.
because particle collide more frequently with
more energy as higher proportion of particles
have energy higher than the activation energy.
C8.4The effect of concentration or pressure.
Increasing the concentration of the
solution or pressure of gas increases
the rate of reaction
because there are more
particles closer to each other
therefore there will more
collisions for a reaction to occur.
C8.5 the effect of catalysts
A catalysts changes the rate of
reactions but does not change the
products. It is unaffected.
Different catalysts are used
for different reactions
Usually used in industry to
speed reactions up and
reduce energy costs and
help the environment
usually transition metal such as gold, platinum and palladium
Iron for ammonia and platinum for nitric acid
Used in the form of powders, pellets or fine
gauzes to give them most possible surface
area and makes the more effective.