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Activation Energy

The document describes an experiment to determine the activation energy of the reaction between potassium permanganate and oxalic acid. Students will measure the reaction rate at five different temperatures by timing how long it takes the solution to change color. They will use the rate constants calculated from these measurements to plot ln(k) vs 1/T and determine the activation energy from the slope of the line.

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Rahul Choudhary
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416 views1 page

Activation Energy

The document describes an experiment to determine the activation energy of the reaction between potassium permanganate and oxalic acid. Students will measure the reaction rate at five different temperatures by timing how long it takes the solution to change color. They will use the rate constants calculated from these measurements to plot ln(k) vs 1/T and determine the activation energy from the slope of the line.

Uploaded by

Rahul Choudhary
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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To Determination the Energy of Activation

In today’s experiment you will study the reaction between potassium permanganate and dilute oxalic acid at
different temperatures. The permanganate ion MnO4- reduces to MnO2 changing the color from bright
purple/pink to yellow/brown. You will find the rate constant for this reaction at five different temperatures and
then determine the activation energy for the reaction.

PRECAUTION: DO NOT TOUCH THE WATER IN THE WATER BATH

Procedure:
1. Using burettes, place 20 mL oxalic acid (0.5 M) in a conical flask and 10 mL KMnO4 (approximately
0.02 M) in a test tube. The exact concentration of KMnO4 should be noted from the blackboard.
2. Place both the vessels in a water bath to equilibrate for at least 5 minutes.
3. Mix the reactants in the conical flask and start the stop watch.
4. Swirl the reaction mixture regularly without taking it out of the water bath.
5. Record the time it takes for the mixture to turn yellow/brown.
6. Repeat the procedure with another sample at this temperature.
7. Repeat steps 1 to 6 for three other temperatures.
8. For the reading at 0 degree Celsius, time taken is 2160 seconds. Use this information as the fifth
temperature reading in your experiment.
9. Determine the activation energy by plotting ln k Vs 1/T. (Temperature in degree kelvin)

Data collection should consist of a table similar to:


[KMnO4] = [Oxalic Acid] =
Observation and Calculations:

S. Temp Temp 1/T Time Time Average Rate= k ln


No. ( ͦ C) (K) for for Time [KMnO4]/time =Rate/[KMnO4][Oxalic] (k)
trial trial (s)
1 (s) 2 (s)
1
2
3
4
5
6
7
8
9
10

Show sample calculation for determining the rate: Rate = [KMnO4]/time.


Show sample calculation for determining k: k =Rate/[KMnO4][Oxalic].

Plot of ln k Vs 1/T and determine Ea in kJ/mol from the slope.

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