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Unit 6: The Rate and Extent of Chemical Change - Coggle Diagram
Unit 6: The Rate and Extent of Chemical Change
Rate of Reaction
Calculating rate
quantity of reactant used/ time
Units are cm^3 / second, g/s, mol/second
Factors that affect
rate of reaction
Temperature
Increasing the temperature increases the Ke of the particles.
Thus more particles have
energy equal or greater than the activation energy
therefore an
increase in frequency of successful collisions thus higher rate of reaction.
Concentration
If the
concentration of a solution is increased,
there are
more particles in a given volume,
increasing the rate by
causing more frequent successful collisions
Surface area
Small pieces have a larger surface area
than big chunks. Larger surface area means that there are
more particles available to react
so
more frequent successful collisions occur.
Pressure
(ONLY GASES)
If the
pressure of a gas is increased,
the
particles are forced closer together
causing
more frequent successful collisions
INCLUDE MORE
FREQUENT SUCCESFUL COLLISIONS
IN EVERY ANSWER
Catalyst
A
catalyst speeds up a reaction without changing itself.
Catalysts work by
lowering the activation energy
needed by providing an
alternate pathway for the reaction.
Raj's Matchmaker analogy
Extent of Reaction
Effect of Changing
Concentration
Increased
concentration of
reactant
According to
Le Chatelier's principle
, the
system acts to oppose the increase the concentration.
And so, the position of the
equilibrium shifts to the right-hand side
to
use up excess reactiants.
Thus, an
increase
in product yield
.
Decreased
concentration
of
reactant
According to
Le Chatelier's principle
, the
system acts to oppose the decrease in concentration.
And so,
the position of equilibrium shifts to the left-hand side
to
replace lost reactants.
Increased
concentration of
product
According to
Le Chatelier's principle
, the
system acts to oppose the increase of concentration.
And so, the position of
equilibrium shift to the left hand side
to
use up excess products.
Decreased
concentration of
product
According to
Le Chatelier's principle
, the
system acts to oppose the decrease in concentration
. And so, the position fo the
equilibrium shifts to the right-hand side
to
replace the lost products
. Thus, an
increase in yield of products
Effect of changing
temperature
Forward reaction is
exothermic
Increase
in temperature
Equilibrium shifts to oppose the increase in temperature
. Reaction that
absorbs extra heat is favoured
(
Endothermic)
Equilibrium
shifts to the
left hand side.
Decrease
in temperature
Equilibrium shifts to oppose the decrease in temperature
. Reaction that
gives out more heat is favoured (
exothermic
)
.
Equilibrium
shifts to the
right-hand side
. Thus, an
increase in product yield
.
Forward reaction is
endothermic
Increase
in temperature
Equilibrium shifts to oppose the increase the temperature
. Reaction that
absorbs extra heat is favoured (
endothermic
)
.
Equilibrium
shifts to the
right-hand side
. Thus, an
increase in product yield
Decrease
in temperature
Equilibrium shifts to oppose the decrease in temperature
. Reaction that
gives out extra heat is favoured (
exothermic
).
Equilibrium
shifts to the
left-hand side
.
Effect on Changing
Pressure
More gas molecules of reactants
Increase
in pressure
Equilibrium shifts to
oppose the increase in pressure
. Reaction that
produces less moles of gas is favoured
to
reduce the pressure
.
Equilibrium shifts to the right hand
side
.
Thus, an
increase
in product yield
.
Decrease
in pressure
Equilibrium shifts to
oppose the decrease in pressure
. Reaction that
produces the most moles of gas is favoured
to
increase the pressure
.
Equilibrium shifts to the left-hand side.
Same number of gas molecules on both sides
Position of Equilibrium
does
not change
More gas molecules of product
Increase
in pressure
Equilibrium shifts to
oppose the increase in pressure
. Reaction that
produces the least moles of gas is favoured
to
reduce the pressure
.
Equilibrium shifts to the left-hand side
Decrease
in pressure
Equilibrium shifts to
oppose the decrease in pressure
. Reaction that
produces the most gas molecules is favoured
to
increase the pressure
.
Equilibirum shifts to the right-hand side
. Thus, an
increase
in product yield.