How does temperature affect the rate of aggregation of colloidal gold?
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 History of Colloidal Gold Appearance in the Old Testament of the Bible (Exodus 32) Alexandria, Egypt Ancient Rome Used for photography in 1842 in the process of crysotype
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. 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 Why does Colloidal Gold turn Blue after Aggregation? Because of the change in the light spectra 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 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
1. Measure 20 mL of 1mM hydrogen tetrachloroaurate solution in a graduated cylinder 2. Pour the 20 mL of 1mM hydrogen tetrachloroaurate solution into a 250 mL Erlenmeyer Flask 3. Add distilled water to the 200 mL mark on the Erlenmeyer flask 4. Place the Erlenmeyer flask onto a hot plate and turn the hot plate on a medium-high setting 5. Bring to a gentle boiling 6. Measure 2mL of 1% trisodium citrate solution using a 10 mL graduated cylinder 7. Add the 2mL of 1% trisodium citrate solution to the boiling solution in the Erlenmeyer flask 8. 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 9. After the color stabilizes, remove the Erlenmeyer flask from the hot plate and allow to cool 10. 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 Dependent variable: Aggregation rate Control: Room temperature Constants: Colloidal gold and amount of sodium chloride solution added
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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