Saturday, 28 July 2012
Failed experiment
The reason for the failure of the first experiment was due to difficulty in finding the right experiment procedure. I tried out once, however, it failed badly, lasting only about 1 to 3 secs. Therefore, a new experiment was thought of.
The references
I also made other references of the journals of the food science in the National Library, from the Lee Kong Chian Reference Library.
The process of doing experiment
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| The different starch and the egg |
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| When testing for the thickening measuring the length after 6 hours |
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| Wheat Starch |
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| tapioca starch |
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| corn starch |
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| potato starch |
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| testing for the difference between sugar and salt (the mixture) |
Egg
cartoon 1
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Tapioca
2 teaspoon salt
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Wheat
1 teaspoon sugar
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tapioca
1 teaspoon sugar
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potato
1 teaspoon sugar
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corn
1 teaspoon sugar
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Potato
2 teaspoon salt
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Wheat
2teaspoon sugar
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Tapioca
2teaspoon sugar
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potato
2teaspoon sugar
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corn
2teaspoon sugar
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Egg
cartoon 2
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egg
2teaspoon sugar
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egg
2 teaspoon salt
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corn
2 teaspoon salt
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wheat
2 teaspoon salt
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Egg
1 teaspoon sugar
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Egg
1teaspoon salt
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The background research
When two molecules react
chemically so that there is a release of energy (an exothermic reaction), that
energy sometimes manifests itself not as heat but as light. This occurs because
the energy excites the product molecules into which it has been funneled. A
molecule in this excited state either relaxes to the ground state, with the
direct emission of light, or transfers its energy to a second molecule, which
becomes the light emitter. This process is referred to as chemiluminescence.
The originally green, now multicolored, commercially made "light
sticks" (often in the form of bracelets and necklaces) work in this way,
utilizing the (exothermic) reaction of hydrogen peroxide with an oxalate ester .
This oxidation reaction produces two molecules of carbon
dioxide (CO 2 ), and the released energy is transferred to
a fluorescent dye molecule, usually an anthracene derivative. Light sticks were
developed by the U.S. Navy as an inconspicuous and easily shielded illumination
tool for special operations forces dropped behind enemy lines. Besides their
use as children's toys, they are also used extensively as a navigation aid by
divers searching in muddy water.
These light sticks glow
as a result of the energy released by a chemical reaction.
Chemiluminescence is
also found in fireflies. The male firefly uses the reaction of a luciferin
substrate and the enzyme luciferase with oxygen, with adenosine
triphosphate (ATP) as an energy source, to create the illumination it
uses to attract a mate. Because the detection of very minute amounts of light
is possible, chemiluminescence and bioluminescence have become the basis of
many sensitive analytical and bioanalytical techniques or assays used to
quantify particular compounds in samples. Indeed, the use of these techniques
is broad enough to justify the existence of a journal devoted to them,
the Journal of Bioluminescence and Chemiluminescence.
In 1669 Hennig Brand, a
German alchemist, was attempting to recover, by means of intense heat, the gold
he hoped was lurking in human urine. The waxy white substance that he did
retrieve, which glowed green when exposed to air, was in fact elemental
phosphorus.
The emission of light
observed by Brand was actually chemiluminescence. The light arises from
PO 2 molecules in an excited state. This excited state of
PO 2 is brought about by the reaction between PO and
ozone, which are both intermediates in the fundamental
reaction between oxygen in air and P 4 vapor evaporating
from the solid white phosphorus. It is unfortunate that the chemiluminescent
glow of phosphorus gave rise to the term
"phosphorescence."
Scientifically, phosphorescence is a process whereby absorbed photons are
emitted at a later time, as exemplified by the glow of a watch face in the dark
after its earlier exposure to light.
Luminol
(3-aminophthalhydrazide) is used in a commercially available portable device
called the Luminox that measures minute concentrations (parts per billion) of
the pollutant nitrogen dioxide in air. Luminol is also used frequently in
laboratory demonstrations of the chemiluminescence phenomenon. Luminol-mediated
chemiluminescence is the result of an oxidation reaction. The oxidation
proceeds in two steps, which ultimately lead to the production of the
aminophthalate anion in an excited state and the elimination
of water and molecular nitrogen. The formation of the strong triple bond (N≡N)
is a major factor in the release of energy in the form of light.
Probably the simplest
chemiluminescent reaction (and one that has been studied extensively) is the
reaction between nitric oxide , NO, and ozone, O 3 .
The reaction (with about 10% efficiency) yields nitrogen dioxide in an excited
state (NO 2 *)
NO + O 3 =
NO 2 * + O 2
NO 2 *
= NO 2 + h ν
The reaction was
developed in the early 1970s as a specific and instantaneous method to detect
nitric oxide in the exhaust of automobiles. This use of chemiluminescence
rapidly led to application of the same phenomenon to monitor the presence of NO
in the atmosphere. Both applications continue in use. Ozone can easily be
produced by passing dry air or oxygen through an electric discharge. The
ozone-containing stream and the sample to be evaluated are mixed in a dark
chamber adjacent to a photomultiplier tube, and the chemiluminescence signal
that is produced is amplified. These devices are capable of monitoring NO
levels ranging from parts per trillion to thousands of parts per million; an
individual instrument can sometimes measure concentrations extending across six
orders of magnitude.
The familiar yellow glow
from a natural gas or wood-burning flame is not the result of
chemiluminescence, but is due to bright, red-hot particles of carbon soot. The
blue, green, and other colors produced when metals are put
into flame can indeed be ascribed to chemiluminescence; in these instances the
luminescence is accompanied by heat production.
According to information
provided by the Harbor Branch Oceanographic Institution in Ft. Pierce, Florida,
more than 90 percent of organisms living in the oceans at depths from 200 to
1,000 meters (656 to 3,281 feet) use chemiluminescence for activities such as
attracting prey and avoiding predators. Light from the sky is quite weak at
those depths; a fish that emits a dim glow from its lower parts could become
invisible from below, while a fish without this capability would appear as a
dark shadow.
Donald H. Stedman
Planning Process of the the experiment
Planning for the experiment
Area of
experiment- measuring the duration of phosphorescence can last
when exposed under Uv rays.
w Find
UV light/ Uv lamp to provide the UV rays needed.
w Measuring
the duration the glow-in-the-dark can last in the dark after being exposed to
UV light.
w Find
the phosphorescence material
w Find
the difference between flouroescence and phosphorescence
Area of
experiment –measuring if the amount of chemical in the light stick
would allow it to last longer
w Find
the chemical in the light stick
w Find the
ratio of the chemical needed and the effect of each of them when combined.
Proposal for the chemiluminescence
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A
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Observations made
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I
observed that light stick in the chemiluminescence
enables the light stick to last longer than glow-in-the-dark that phosphorescence
is present in.
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B
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Research Question
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Does
Chemiluminescence last longer than phosphorescence
exposed under Ultraviolet
Rays?
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C
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Hypothesis statement
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Chemiluminescence last longer
than phosphorescence exposed under Ultraviolet rays.
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D
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A short summary of research done on the area of
investigation
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Research
shows that phosphorescence exposed under Ultraviolet rays
last longer than phosphorescence under normal light. Chemiluminescence occurs
due to chemical reaction while phosphorescence occurs only when it absorbs
the radiation, and then it re-emits
the radiation
at lower intensity for up to several hours after the original excitation.
Phosphorescence
Phosphorescence occurs
when energy in light waves is absorbed by a phosphorescent material and later
released in the form of light, at a very slow rate. This slow release of
light energy is what causes the glow-in-the-dark sticker to continue glowing
over a period of time.
When ultraviolet light is absorbed by the phosphorescent material, electrons in the atom become"excited". These electrons will eventually return to their normal energy levels, gradually. It is during this gradual process of electron state "degradation", that the material is seen to glow.
Chemiluminescence- present in light sticks
Lightsticks or glowsticks are used by
trick-or-treaters, divers, campers, and for decoration and fun! A lightstick
is a plastic tube with a glass vial inside of it. In order to activate a
lightstick, you bend the plastic stick, which breaks the glass vial. This
allows the chemicals that were inside the glass to mix with the chemicals in
the plastic tube. Once these substances contact each other, a reaction starts
taking place. The reaction releases light, causing the stick to glow!
Chemiluminescence is the production of light from a
chemical reaction. Two chemicals react to form an excited (high-energy)
intermediate, which breaks down releasing some of its energy as photons of light (see glossary for all terms
in bold) to reach its ground state
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E
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Bibliography (Please refer to RS Students’ Handbook in RS Folder on
Inet regarding APA Style Format)
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