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C6 - Rates of Reaction and Equillibrium - Coggle Diagram
C6 - Rates of Reaction and Equillibrium
L1 - Rates of Reaction
Mean reaction time = Quantity of reactant used / Time
Mean reaction time = Quantity of product made / Time
We can measure the
rate of chemical reaction
by
observing the time taken for
:
mass to be lost as a gas
, gas(
volume) to be produced and collected
or for
a colour change to occur.
Method
:
Put
two spatulas
of
solid reactant
into a weighing boat,
subtract the mass of the weighing boat from the total mass
.
-
Measure
out an
acid of a fixed volume
and
fixed concentration
using equipment of a
suitable resolution.
-
Pour the
HCl
into a
conical flask
and
add the solid into the flask
also,
bung the flask immediately
and
begin a stopwatch.
-
Measure
the
volume of gas
that is
produced
(as stated by the
gas syringe
)
per unit time.
-
Repeat
this several times to
ensure results are not anomalous
. Remove results that are and
calculate a mean volume
produced.
L2 - Rate Graphs
When the
volume of gas produced
or
mass lost becomes constant
; one or more of the
reactants
has been
used up.
To find the
gradient
at a
particular point
;
draw a tangent
that touches a graph/function at that point. Calculate the
gradient of that tangent
for an estimate of the rate at that point.
L3 - Factors Affecting Rate of Reaction
Rate of reaction
is defined as
how quickly reactants can be turned into products.
Factors
affecting
rate of reaction
include:
temperature
,
concentration/pressure
,
catalysts
,
surface area.
If
collision frequency is higher,
there will be a
greater rate of reaction
(there is a
greater amount
of
successful collisions per unit time
).
Particles
must
collide with enough energy
for a reaction to ensue (minimum is known as
activation energy
).
If a solution is
more concentrated,
there are
more reactant particles per unit of volume
. This means that there will be
more successful collisions per unit time
; the same is true with pressure in gasses.
If there is a
larger surface area to volume ratio
, there will be a
greater surface area
on which
particles can collide
.
A
catalyst increases
the
rate of reaction
by
providing an alternative
,
lower energy "pathway"
for a reaction; this
decreases activation energy
, meaning that there will be successful collisions will be easier to achieve.
L4 - Effect of Concentration on Rate of Reaction (Cross Method)
Method:
Add a
fixed volume of sodium thiosulphate
into
measuring cylinder
of appropriate resolution.
-
Pour the
sodium thiosuphate
into a conical
flask
.
-
Place
the
flask onto a cross
which has been drawn onto the table.
-
Measure out a
fixed volume and concentration of acid
using a
measuring cylinder
of appropriate resolution.
-
Pour
the
acid into the conical flask
and immediately
begin a timer
; stop the timer when the
cross is no longer visible.
-
Repeat
for
differing concentrations
of
sodium thiosulphate.
Rate = 1/Mean Time
L5 - Effect of Concentration on Rate of Reaction (Cylinder Method)
Method
:
Set up apparatus:
upturned measuring cylinder filled with water,
pipe
leading
from bung to
underneath
the
cylinder
.
-
Add
magnesium ribbon of a fixed length
to a conical
flask
.
-
Measure
out some
HCl
of a fixed
volume
and the
first molar value
.
-
Pour
the
HCl into the flask
,
start the stopwatch
and immediately
bung the system
to prevent the escape of gas.
-
R
text
ecord the
volume of gas produced
every set
time increment
.
-
Repeat
with
differing molar values of HCl
.
L7 - Equilibrium Shifting
When a
reaction is
deemed "
reversible
"; the reaction
can only occur both ways if
kept in
a closed system
(
energy is not lost or gained
).
A
reversibility
symbol means that the
reaction is in equilibrium.
A
dynamic equilibrium
is a
state of equilibrium
that is
always moving/alternating
.
In certain conditions, the
equilibrium can lean slightly
to one side;
producing more products on that side.
Le Chatelier's Principle
states that the
equilibrium will shift
to
oppose any changes
that are made.
Take the equation:
A + B <---> C + D
(-> = Exo, <- = Endo)
-
If the
concentration of A increases
, the
concentration of C and D must increase
to
counteract the change.
-
If the
temperature increases
, an
endo reaction must take place
to
counteract the change.
-
If the
pressure increases
(provided all are gaseous), the
equilibrium will shift
to the
side with lesser mols of gas.