After completing this topic you should be able to :
• understand that the rate of some reactions
can be increased using a catalyst
• Learn how a catalyst speeds up reaction rate
by lowering the activation energy, and how to
represent this on a potential energy diagram.
• Devise an experimental investigation into the
decomposition of hydrogen peroxide.
Here is the runaway bestseller that launched Tom
Clancy's phenomenal career. A military thriller so
gripping in its action and so convincing in its accuracy
that the author was rumoured to have been debriefed
by the White House.
Its theme: the greatest espionage coup in history. Its
story: the chase for a top secret Russian missile sub.
Lauded by the Washington Post as "breathlessly
exciting.“
The Hunt for Red October remains a masterpiece of
military fiction by one of the world's most popular
authors, a man whose shockingly realistic scenarios
continue to hold us in thrall.
Somewhere under the Atlantic, a Soviet sub
commander has just made a fateful decision. The Red
October is heading west. The Americans want her. The
Russians want her back. And the most incredible chase
in history is on..
The novel was made into a commercially successful
movie in 1990.
K-141 Kursk was an Oscar-II class nuclear-powered cruise missile submarine of
the Russian Navy, lost with all hands when it sank in the Barents Sea on 12 August
2000. Kursk, full name Атомная подводная лодка «Курск», which, translated, means
the nuclear-powered submarine "Kursk" [АПЛ "Курск"] in Russian, was a Project 949A
Антей (Antey, Antaeus, also known by its NATO reporting name of Oscar II). It was
named after the Russian city Kursk, around which the largest tank battle in history,
the Battle of Kursk, took place in 1943 (world war 2). One of the first vessels completed
after the end of the Soviet Union, it was commissioned into the Russian
Navy's Northern Fleet.
Starter Activity
• Pupils to work in groups (2-4)
• Pupils to be given the News timeline and Arces Worksheet
• Issue a mini whiteboard to each group and ask them to write
down what information they can deduce from the table and
timeline.
Many points arise here but they should include
that the sinking of the Kursk involved hydrogen
peroxide.
There were two explosions at roughly the same
place in quick succession, the second more
powerful than the first.
Hydrogen Peroxide Demonstration
Pose questions to highlight that the decomposition:
• has been accelerated by the presence of a catalyst
• occurs at a sufficiently high temperature to vaporise
the water
• proceeds at a very fast rate, rather like an explosion.
(emphasize to pupils that ours is not
HTP High-test peroxide or HTP is a high
(85 to 98 percent)-concentration solution
of hydrogen peroxide, with the remainder
predominantly made up of water. In contact
with a catalyst, it decomposes into a hightemperature mixture of steam and oxygen,
with no remaining liquid water. It was used
as a propellant of
HTP rockets and torpedoes, and has been
used for high-performance vernie engines.)
Click Here
Potential energy graphs and catalysts
Uncatalysed
75 -
60 50 -
Reactants
Catalysed
P.E.
Products
25 -
Reaction path
Potential energy graphs and catalysts
Activation energy Ea for the forward uncatalysed reaction
75 -
60 -
Activation energy Eafor the
forward catalysed reaction
Reactants
50 -
P.E.
Products
25 -
Reaction path
Catalysts lower the activation energy needed for a successful collision.
Potential energy graphs and catalysts
Activation energy Ea for the reverse uncatalysed reaction reaction
75 -
Activation energy Ea for the
reverse catalysed reaction
60 50 -
Reactants
P.E.
Products
25 -
Reaction path
Catalysts lower the activation energy needed for a successful collision.
Potential energy graphs and catalysts
75 -
Catalysts lower the activation
energy needed for a successful
collision.
60 50 -
Reactants
P.E.
Products
25 -
Reaction path
∆H
Activation energy
Effect of catalyst – forward reaction
No change
Lowered
Effect of catalyst – reverse reaction
No change
Lowered
Catalysts
A catalyst speeds up the reaction by lowering the
activation energy.
A catalyst does not effect the enthalpy change for a
reaction
A catalyst speeds up the reaction in both directions
and therefore does not alter the position of
equilibrium or the yield of product, but does decrease
the time taken to reach equilibrium.
Energy distribution and catalysts
Ea
No of
Collisions
with a
given
K.E.
Un-catalysed reaction
Kinetic energy
Ea
Total number of collisions (area under
the graph) with sufficient K.E.
energy to create new products.
Catalysed reaction
Ea is reduced
Explain that they are to plan an experiment to compare how effective
different powders are in catalysing the decomposition of hydrogen
peroxide.
• Take the students through the equipment and materials that are available.
• Give each student a What sank the Kursk? Worksheet and an Apparatus list.
• Ask them to draw a diagram of their apparatus for when they begin their
experiment.
• After a suitable time, give out copies of the Apparatus diagram, showing the
expected apparatus.
• Pose questions to make explicit why that apparatus has been chosen.
• Ask the students to compare their diagram with the one they have been
given.
• Get them to write down an experimental procedure based on the Apparatus
diagram they have been given (and which someone else could follow).
• After a suitable time give out copies of the Procedure sheet detailing the
expected procedure.
• Pose questions to highlight why the procedure has been chosen.
• Ask students to compare their experimental procedure with that on
the Procedure sheet.
Apparatus list
The equipment available to investigate
the effect of different powders on the decomposition of
hydrogen peroxide
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Trough
50 m3 burette which will be inverted
250 cm3 conical flask with bung fitted
About 75 cm3 of 20 volume hydrogen peroxide per test (Irritant)
Range of powders to test
Small test-tube
Rubber tubing to connect side arm of flask to bottom of upturned
burette
Boss, clamp and stand
Stop clock
Cotton thread
Funnel
100 cm3 measuring cylinder
Balance weighing to 0.01 g
Eye protection.
Procedure to investigate
how powders effect the rate of decomposition of hydrogen peroxide
•Half fill a trough with water.
•Fill a burette with water, cover the open end with your thumb and upturn so the end is below the
surface of the water.
•Clamp the burette using a clamp, boss and stand.
•Measure 75 cm3 of 20 volume hydrogen peroxide with a measuring cylinder and pour into a
conical flask.
•Connect the side arm of the flask to the bottom of the burette with rubber tubing.
•Weigh out between 0.3 and 0.5 g of powder and put this into the small test-tube.
•Tie one end of thread around the test-tube and suspend it above the hydrogen peroxide in the
flask.
•Simultaneously loosen the bung to drop the test-tube into the flask and start the stop clock.
•Record the level of water in the burette every 20 seconds for 5 minutes or until the water level
goes below the level of the burette.
Time
/s
20
40
60
80
100
Burette
reading
/ cm3
Time
/s
120
140
160
180
200
Burette
reading
/ cm3
Time
/s
220
240
260
280
300
Burette
reading
/ cm3
Concentrated solutions of hydrogen peroxide are used in the
propulsion systems of torpedoes. Hydrogen peroxide
decomposes naturally to form water and oxygen:
2H2O2(aq) → 2H2O(ℓ) + O2(g)
ΔH = −196∙4 kJ mol–1
Transition metal oxides act as catalysts in the decomposition of
the hydrogen peroxide.
Unfortunately, there are hazards associated with the use of
hydrogen peroxide as a fuel in torpedoes. It is possible that a
leak of hydrogen peroxide solution from a rusty torpedo may
trigger an explosion.
Using your knowledge of chemistry, comment on why this could
happen.
Discuss with pupils in groups expectations of open-ended
questions and their responses.
An official investigation after most of the wreck was raised along with analysis of pieces
of debris concluded that a faulty weld in the casing of the practice torpedo caused hightest peroxide (HTP) to leak, which caused the kerosene fuel to explode. The initial
explosion destroyed the torpedo room, severely damaged the control room,
incapacitated or killed the control room crew, and caused the submarine to sink. The fire
resulting from this explosion in turn triggered the detonation of between five and seven
torpedo warheads after the submarine had struck bottom. This second explosion was
equivalent to between 2 to 3 tonnes (2.0 to 3.0 long tons; 2.2 to 3.3 short tons) of TNT. It
collapsed the first three compartments and all the decks, and destroyed compartments
four and five, killing everyone forward of the nuclear reactor compartment. An alternative
explanation offered by critics suggested that the crew was not familiar with nor trained
on firing HTP torpedoes and had unknowingly followed preparation and firing
instructions intended for a very different type of torpedo. Combined with poor oversight
and incomplete inspections, the sailors initiated a set of events that led to the explosion.
And the sea will grant each
person new hope, as sleep
brings dreams of home.