User:Elizabeth Schott/Notebook/Nanoparticles/2015/06/01

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  Stock Solution: Sodium Citrate (Na2C4H5O7 * 2H2O) 

A 1%(w/v) stock solution of sodium citrate was prepared for this experiment. 1.053 g of sodium citrate was weighed in a plastic wayboat on a scale and transferred into a 50 mL beaker. The wayboat was rinsed with water and emptied into the 50 mL beaker to ensure maximum sodium citrate transfer. Water was added to the 50 mL beaker and was stirred to dilute the solvent. The solution was then transferred into a 100 mL volumetric flask. The remaining space in the flask was filled with water and stirred. This solution was emptied from the volumetric flask into a sealed container and labeled.

  Stock Solution: Gold Solution (HAuCl4) 

This .001 mM stock solution was modified to use HAuCl4 in place of HAuClr*3H2O (see calculations 1). 0.17 g of HAuCl4 was weighed in a plastic wayboat on a scale and transferred into a 50 mL beaker. The wayboat was rinsed with water and emptied into the 50 mL beaked to ensure maximum transfer. Water was added to the 50 mL beaker and was stirred to dilute the solvent. The solution was then transferred into a 500 mL volumetric flask. The remaining space in the flask was filled with water and stirred. This solution was emptied from the volumetric flask into a sealed container and labeled.


Procedure

1) A hot plate was obtained and placed under the fume hood, with heat set to level 4 and stirring set to level 2. 2) A 50 mL beaker and stirring rod were obtained. After placing stirring rod in beaker, 22 mL of water was measured using a graduated cylinder and transferred into the beaker. The water line was then marked, and the water was disposed. Using a graduated cylinder, 20 mL of the stock gold solution was measured and transferred into the beaker containing the stirring rod. This beaker was then placed on the hot plate in the fume hood and a timer was set. 3) When the solution in the beaker began to boil, the time since placement was recorded. Using a P1000 micro-pipette, 2 mL of the stock sodium citrate solution was added into the beaker. The time of color change from light yellow to purple was then recorded. 4) Water was added to the solution using a transfer pipette to keep water line at marked level. 5) Solution was left to change into a dark red color, which it was then removed and the time recorded.


Results

The first table shows the times at which the sodium citrate was added to the gold solution, the time of color change from light yellow to dark purple, and the time removed from the hot plate when the color appeared dark red. The average time for color change was approx 49 seconds after the addition of sodium citrate, and the average time of removal was after 12 minutes and 23 seconds.The second table shows raw data calculations, with an average size of 15.05 nm and a standard deviation of 7.27 nm. The third table shows baselined data calculations, with an average size of 14 nm and a standard deviation of 6.99 nm.


Discussion


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