Shannon Cattie
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How does temperature affect the rate of
aggregation of colloidal gold?
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What is Colloidal Gold?
 Binary liquid mixture, containing gold nanoparticles
 Can be ingested orally to treat arthritis, hypertension, skin
conditions, heart rhythm, depression, inflammation,
circulation, pain and stress relief, nerve complaints, and
act as an IQ booster
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History of Colloidal Gold
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Appearance in the Old Testament of the Bible (Exodus 32)
Alexandria, Egypt
Ancient Rome
Used for photography in 1842 in the process of crysotype
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Nanotechnology
 Deals with processes that take place on the
nanometer scale, which is one billionth of a meter.
 Properties of metals are different on the Nano scale
than in bulk.
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Aggregation
 The formation of aggregates causing a change in
color
 For the most part, irreversible
 An aggregate is a group of particles which are held
together; they can be held together in any way

Why add Salt to Aggregate Colloidal Gold?
 Gold particles in colloidal solutions are negatively charged,
so they repel each other. They cannot clump together.
 Salt shields negative charges, causing clumping
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Why does Colloidal Gold turn Blue after Aggregation?
 Because of the change in the light spectra
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Salt (NaCl)
 Suppose to lower the temperature in which aggregation
occurs
 Enhances aggregation

If the temperature of colloidal gold is raised,
then the particles of the colloidal gold will
aggregate more readily than those at lower
temperatures.
TO MAKE THE COLLOIDAL
GOLD
20 mL of 1mM hydrogen
tetrachloroaurate solution
 Distilled water
 2mL of 1% trisodium
citrate solution
 Hot plate
 Erlenmeyer flask
 Graduated cylinder
 Crucible tongs
 Aluminum Foil
 Refrigerator
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FOR EACH TRIAL
Cuvette and cap
1000 μL of 1 M sodium
chloride solution
 3mL of colloidal gold
 100μL of the solution
 Vernier Spectro-vis
 Vernier Logger Pro
Software
 10 mL Graduated Cylinder
 Micropipette
 Thermometer
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1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Measure 20 mL of 1mM hydrogen tetrachloroaurate solution in a
graduated cylinder
Pour the 20 mL of 1mM hydrogen tetrachloroaurate solution into a 250 mL
Erlenmeyer Flask
Add distilled water to the 200 mL mark on the Erlenmeyer flask
Place the Erlenmeyer flask onto a hot plate and turn the hot plate on a
medium-high setting
Bring to a gentle boiling
Measure 2mL of 1% trisodium citrate solution using a 10 mL graduated
cylinder
Add the 2mL of 1% trisodium citrate solution to the boiling solution in the
Erlenmeyer flask
Continue heating the solution at a gentle boil for about 10 minutes until the
solution is stable at a ruby or wine-red color and no longer changes color
After the color stabilizes, remove the Erlenmeyer flask from the hot plate
and allow to cool
Add distilled water until the solution reaches 200 mL again
1.
Begin by hooking up the spectrometer to the computer and opening
Logger Pro
2.
Measure 3 mL of Colloidal gold into a 10 mL graduated cylinder
3.
Pour it into a cuvette
4.
Cap the cuvette, wipe the sides of excess liquid, and place into the
spectrometer
5.
Locate the peak of absorption on the graph and record
6.
Heat colloidal gold to 30°C by using a hot plate, let sit for the day and
accumulate to room temperature (10°C), or place in refrigerator and cool
to 10°C
7. Record the peak absorption on each
graph after following this procedure:
a. Add colloidal gold to the cuvette
b. Place into Spectro-vis
c. Record peak absorption
d. Measure 100 microliters of sodium
chloride solution using a micropipette
e. Add the 100 microliters of sodium
chloride solution into the cuvette
f.
Shake the cuvette once, and let sit for
approximately 20 seconds
g. Return to Spectro -Vis and record peak
absorbtion
h. Repeat steps d-g nine times

Independent variable: Sodium chloride
solution
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Dependent variable: Aggregation rate

Control: Room temperature

Constants: Colloidal gold and amount of
sodium chloride solution added
Colloidal Gold at 10°C
Colloidal Gold at 10°C
800
800
700
600
600
Peak of Graph (nm)
Peak of Graph (nm)
R² = 0.8565
700
500
400
300
500
400
300
200
200
100
100
0
0
0
100 200 300 400 500 600 700 800 900 1000
Sodium Chloride Solution (μL)
0
100 200 300 400 500 600 700 800 900 1000
Sodium Chloride Solution (μL)
Colloidal Gold at 20°C
Colloidal Gold at 20°C
800
800
700
600
600
Peak of Graph (nm)
Peak of Graph (nm)
R² = 0.785
700
500
400
300
500
400
300
200
200
100
100
0
0
0
100 200 300 400 500 600 700 80 900 1000
Sodium Chloride Solution (μL)
0
100
200
300
400
500
600
700
Sodium Chloride Solution (μL)
80
900 1000
Colloidal Gold at 30°C
Colloidal Gold at 30°C
800
700
R² = 0.8773
700
600
500
Peak of Graph (nm)
Peak of Graph (nm)
600
500
400
300
400
300
200
200
100
100
0
0
0
100 200 300 400 500 600 700 800 900 1000
Sodium Chloried Solution (μL)
0
100
200
300
400
500
600
700
Sodium Chloried Solution (μL)
800 900 1000
Rate of Aggregation Between Three Temperatures
700
650
Peak of Graph (nm)
600
10C
550
20C
30C
500
450
400
0
100
200
300
400
500
600
Sodium Chloride Solution (μL)
700
800
900
1000
Possible Errors:
 The testing took place on different days


o Slight temperature, humidity, and weather change
Change in temperature as the trials were in
progress
Temperature of sodium chloride solution
Improvements to this experiment:
 Make the sodium chloride solution the same
temperature as the colloidal gold, removing any
difference in temperature between what was
recorded
 Monitor the solution temperature during
procedure



The data received showed all three
temperatures aggregated similarly.
The hypothesis was rejected at the
temperatures tested.
Further testing would be needed to conclude
whether higher temperatures of colloidal gold
increase the rate of aggregation.


Pertains much to recent scientific discoveries
about nanotechnology
Nanotechnologists are testing the ability of
colloidal gold to target cancer tumors.
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