1. By: Anne, Krishna,Trinh,Tao, Manjot, & Sergey

2. Intro: The Importance
Knowledge of the activation
energy and arrhenius
equation for a reaction
allows us to change
variables to increase the
rate at which products are
formed.
Activation Energy with Phosphorus
http://www.youtube.com/watch?v=9rR6OEQR
FZQ&feature=fvwrel

3. Intro: What is Activation Energy?
• Activation energy (Ea):
"the minimum amount of
energy (in kj/mole) that must
be absorbed by a system to
cause it to react"
• Important factors:
• Temperature-an increase
helps the rxn reach the
transition state
• Orientation-the reactants
have to collide in a certain
orientation to react
Chemistry and Chemical Reactivity
Purdue Chemed Reaction Coordinate Diagram
http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch22/activate.html

4. Intro: What did we learn?
Arrhenius Equation: relates temperature (T), orientation (Z) and
the rate constant (K) of the reaction to the activation energy.
http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch22/activate.html#rate
Temperature rule of thumb:
every 10 C increase double in the rate of the reaction

5. Set Up/ Procedure

6. Safety
• ALWAYS wear goggles, gloves, & lab
coat at ALL times during the experiment
• Long hair must be tied back.
• Wear close toed shoes.

7. CAUTION
• If you get any chemical on your hands or
clothes, wash affected area thoroughly
with water for 15 mins.
• Notify instructor immediately.

8. Materials
• 1- 10 ml graduated cylinder
• Small beakers
• Small & large test tubes
• 1 stop watch
• volumetric pipets
• 1 thermometer
• 10 ml of 0.0100M KI
• 10 ml of 0.00100M Na2S203
• 10 ml of 0.0400M KBrO3
• 10 ml of 0.100M HCl
• 1 ml of 0.5% starch

9. Set Up
• Use small beakers & estimate volumes from the
markings on the beakers when getting
reagents. DO NOT WASTE REAGENTS.
• Bring reagents to work area in clean, labeled
appropriate containers.

10. Cont. Set Up
• Put 50 ml of DI water in a beaker.
• Use 1 graduated cylinder and 1 transfer pipet
for EACH REAGENT.
– Make sure they are clean and dry to start. If not,
rinse the graduated cylinder and pipet with a small
amt. of reagent
• LABEL EVERYTHING.

11. General Mixing Information
• You will run the reaction 4 times at
diff. temperatures.
• For each run, have the following
ready:
• Test tube #1 : Large test tube
Place 2.0 ml of KI, 2.0 ml of
Na2S2O3 & 2.0 ml of H2O
• Test tube #2 : Small test tube
 Place 2.0 ml of KBrO3, 2.0 ml of
HCl, and 3 to 4 drops of starch
solution

12. Reaction Run # 1 (Room temp)
• Pour the contents of test tube # 2 into test
tube # 1

13. Reaction Run # 2 (10°C)
• Slowly swirl test tube # 1 and test tube # 2
separately for approximately 5 minutes in a
250 mL beaker of water at a temperature of
about 10°C.

14. Reaction Run # 3 (30°C)
• Repeat the experiment at about 30°C,
warming all reactants in a 250 mL beaker to
that temperature before starting the reaction.

15. Reaction Run # 4 (40°C)
• Repeat the experiment at about 40°C,
warming all reactants in a 250 mL beaker to
that temperature before starting the reaction.

16. result?
The rate of reaction roughly doubles for every 10°C rise in
temperature . Higher temperature, faster reaction.
2.78E-07
0.000000139
5.05E-07
9.51E-07
0
0.0000001
0.0000002
0.0000003
0.0000004
0.0000005
0.0000006
0.0000007
0.0000008
0.0000009
0.000001
0 5 10 15 20 25 30 35 40 45
ReactionRate
Temperature
Reaction Rate & Temperature
11.8 C
21.5 C
29.4 C
39.8 C
What is the Results?

17. Why is that ?
• Because of increasing
collision frequency,
and kinetic energy of
particles; therefore,
particles can overcome
the activation energy to
react.

18. y = -6048.8x + 24.304
R² = 0.9992
0
1
2
3
4
5
6
0.0031 0.0032 0.0033 0.0034 0.0035 0.0036
lnk
1/T
Activation Energy
Ln k 3.77 3.08 4.37 5.00
1/T 0.00339 0.00351 0.00330 0.00319
The Arrhenius Plot
y = mx + b
m=-Ea/R
E= 5.0 x 10^4
(J/mol)

19. Conclusion
• Did the results match your hypotheses?
• Arrhenius Equation is supported by our
experiment

20. Conclusion

21. Conclusion
• Sources of Error?
• How can we improve the lab?

22. Learning Experiences!
• In this experiment we learned that before
any reaction can start, molecules of the
reactants have to bump or collide into
each other. This collision must be strong
enough to cause the reactants to smash
into each other with a certain amount of
energy or the reaction will not occur.
• To form new bonds in the product, old
bonds must break in the reactants, and
breaking bonds takes energy. To start any
chemical reaction, a minimum amount of
energy is needed. This is also known as
the Activation Energy!
• That’s exactly why we use the “The
Arrhenius equation” k = Ae-Ea/RT , it
gives the relationship between the
temperature, T, and the rate constant, k. A
is a constant proportional to the collision
frequency. Ea is the activation energy, the
minimum energy required for a successful
molecular collision.

23. Real World?
• One example of a reaction
that needs energy to start is
the burning of gasoline. You
have probably seen movies
in which a car plunges over a
cliff, lands on the rocks
below, and suddenly bursts
into flames. But if some
gasoline is spilled
accidentally while filling a
gas tank, it probably will
evaporate harmlessly in a
short time.

24. Well… It Happens In the Movies?
• Why doesn’t this spilled
gasoline explode as it does in
the movies? The reason is that
gasoline needs energy to start
burning. That is why there are
signs at filling stations warning
you not to smoke. Other signs
advise you to turn off the
ignition, not to use mobile
phones, and not to reenter the
car until fueling is complete.
This is similar to the lighting of
the Olympic Cauldron as you
will witness the next slide.
• No Activation Energy =
No Explosion.

25. Did You Know?
• Another great example of
activation energy are the
Cauldrons that are designed
for each Olympics. Each
cauldron contain highly
flammable materials that
cannot be extinguished by
high winds or rain. However,
they do not ignite until the
opening ceremonies when a
runner lights the cauldron
using a flame that was
kindled in Olympia, Greece,
the site of the original
Olympic Games.

26. Let’s Review!

27. Let’s Review a little bit more..
Hint… You MIGHT have to participate in the next slide 
• The Arrhenius equation, k = Ae-Ea/RT , gives
the relationship between the temperature, T, and
the rate constant, k. A is a constant proportional
to the collision frequency. Ea is the activation
energy, the minimum energy required for a
successful molecular collision.

28. Obviously We Learned
Something, But Did You?
• Lets Try One:
A second-order reaction was
observed. The reaction rate
constant at 276K was found to
be 8.9 x 10-3 L/mol and
7.1 x 10-2 L/mol at 308K. What
is the activation energy of this
reaction?
Activation energy is the
amount of energy required to
initiate a chemical reaction.
The activation energy can be
determined from reaction
rate constants at different
temperatures by the
equation.

29. Solution
• Find The Activation Energy.

30. THE END

31.  Lab Handout – Exp. E: Activation Energy
 Kotz, John C., Paul Treichel, and John Raymond. Townsend. Chemistry
& Chemical Reactivity. 7th Edition. Australia: Brooks/Cole, 2010. Print
 "The Activation Energy of Chemical Reactions." The Activation Energy of
Chemical Reactions. Web. 14 July 2012.
<http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch22/activate
.html >.
 YouTube.com. Web. 14 July 2012 <Activation Energy with
Phosphorus<http://www.youtube.com/watch?v=9rR6OEQRFZQ&feature
=fvwrel>
 "Dnatube Scientific Videos." DnaTube.com.Web. 16 July
2012. <http://www.dnatube.com/video/4887/Activation-energy >
 "Activation Energy Problems ~ Analytical Chemistry." Activation Energy
Problems ~ Analytical Chemistry. Web. 16 July 2012.
<http://www.analyticalchemistrygsu.com/2012/02/activation-energy-
problems.html>
 <http://chem.chem.rochester.edu/~chm132tr/worksheets/workshop_08_
activation.pdf >
 All pictures: Microsoft Office Clip Art - < http://office.microsoft.com/en-
us/images/results.aspx?&ex=2&qu=chemistry>
Works Cited/ References