The Gloves Procedure Preparation: *Prepare the solutions immediately before

The Chemiluminescence
of Luminol

Problem Statement

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            How does the
amount of hydrogen peroxide effect the brightness and duration of the
luminescence of luminol?

Hypothesis

            If the
amount of sodium hydrogen peroxide affects the brightness and duration of the
luminescence of the luminol and the sodium hydroxide solution is increased,
then the brightness and duration of the luminescence of luminol will increase.

Research Summary

Luminol itself holds the purpose of
glowing brightly when in the presence of blood, and is very often used by
detectives and law enforcement officials in the scene of a crime to determine
if there is blood present in the crime scene. However, the purpose of this
experiment includes two causes; showing that the energy of a chemical reaction
can be given out as light as well as heat, and to determine whether the amount
of hydrogen peroxide affects the brightness and duration of the luminescence or
not.

While performing this experiment,
proper safety precautions should be taken as well as proper disposal of the
chemicals afterwards. Even though this experiment has a very safe reaction,
chemicals should be handled carefully with gloves, and goggles worn at all
times, as both the hydrogen peroxide and sodium hydroxide can cause minor irritation
of the skin.

 

 

 

 

Materials

·        
600
mL of water (100 mL for three trials each for stock A)

    (100 mL for three trials each for stock B)

·        
.54
mL of Luminol (.18 g for three trials each for stock A)

·        
9.0
mL of sodium hydroxide solution (3.0 mL for three trials each for stock A)

·        
3
mL of hydrogen peroxide (1 mL for three trials each for stock B)

·        
.09
g of potassium ferricyanide (.03 g for three trials each for stock B)

·        
4
ft. piece of tubing

·        
Funnel

·        
Ring
stand

·        
Support
ring

·        
Clamps

·        
Two
beakers

·        
Goggles
and Gloves

Procedure

Preparation:

*Prepare the solutions immediately before use

To Prepare Stock Solution A:

1.     
Fill
a beaker with 100 mL of water

2.     
In
the same beaker, add .18g of Luminol

3.     
Finally,
add 3.0 mL of Sodium Hydroxide

To Prepare Stock Solution B:

1.     
Fill
a separate beaker with 100 mL of water

2.     
Add
1 mL of hydrogen peroxide and .03g of Potassium Ferricyanide

Procedure:

1.     
Dim
the lights

2.     
Simultaneously
pour an equal amount of solution A and B into the funnel

3.     
As
the two solutions mix, observe and record how bright the luminescence of the
solution appears to be, on a scale of 1-10 (1 being not bright at all, and 10
being very bright) also time and record how long the solution glows.

4.     
Repeat
three times; for each trial, increase the hydrogen peroxide by .4 mL

Data Table

 

Trial One

Trial Two

Trial Three

Averages

Brightness
(On a scale of 1-10, 1 being not bright at all and 10 being very
bright)

5
Fairly
bright, some parts were brighter than others.

7
Beginning
to brighten, some parts still are brighter than others.

10
Very
bright, less parts look to be duller than others.

(Approximately)
7

Duration
(Measured in seconds and minutes)

1:04
(64
Seconds)

1:46
(106
Seconds)

2:13
(133
Seconds)

1:41
(101
Seconds)

 

Graph

Brightness Average: Approximately 7 1/3

Duration Average: 101 seconds

 

Conclusion

            This is experiment was performed in
order to answer the testable question “How does the amount of hydrogen peroxide
effect the brightness and duration of the luminescence of luminol?”. By the
time the data was collected, the answer to the problem statement was that if
the hydrogen peroxide is increased, then the brightness and the duration of the
oxidized luminol. My hypothesis was supported, because in my hypothesis I
predicted that the brightness and duration would increase along with the
hydrogen peroxide. The data that can support this claim, is the average
brightness, a 7 1/3 (based on a 1-10 scale, with one being not bright and ten
being very bright), and the average duration, 101 seconds or 1 minute and 41
seconds.

            Every science experiment will always
include errors. Errors are vital to any experiment in order to make corrections
and learn from our mistakes. In this particular experiment, there were at least
three possible errors that could have occurred; first, the scientist could have
added too little or too much of a solution, which would affect the end result
of the experiment. Another possible mistake could be not reading instructions
carefully enough. This could be a big problem because if even one instruction
is skipped or performed incorrectly, the whole experiment would be thrown off.
Lastly, in mixing the two stocks, A and B, the instructions state to simultaneously
pour them through the funnel. However, it is possible the scientist could have
neglected to pour them exactly at the same time. This could affect the mixing
of the solutions and therefore changing the data results. In order to learn
from errors, they must be recalled in future trials or different experiments.
For example, in order to get clearer results, next time the scientist could
read the instructions more thoroughly and visualize what they must do, before
doing it.

            The importance of this experiment
may not heavily impact regular civilians. However, it encourages the
understanding that energy can produce not only heat, but light without heat. It
also helps chemists and other types of scientists. With the information
provided, scientists can show that sodium hydroxide can oxidize luminol. It can
also prove that the more sodium hydroxide is added, the brighter and longer the
luminol will glow.