Synthesis of Gold Particles and Their Use for Chemical Sensing - Assignment Example

Synthesis of Gold Particles and Their Use for Chemical Sensing Faris Albaiji ENGR-111-A2 10/09/12 The goal of this chemical experiment was to determine the level of gold particles in the solution dissolved. Moreover, the experiment aimed at examining the presence of melamine in the food that we eat. Notably, the used citrate in this experiment has been used to know the source of the gold ions that makes it easier for them to join with each other. The use of nitrates prevents the growth grow because of the negative charges of the gold that covered the upper part.

Addition of the solution into melamine makes the layer jackets to fade. This effect made it clear that the gold was eligible since there was a continued accumulation that was evident by the change in the color of the solution from red to Purple color.Introduction It is important to test the foods sold in commercial markets. Notably, it had been discovered some sold in the commercial markets are toxic. For examples, some years ago, foods containing melamine were found in stores in China. Foods that contain melamine are toxic and are not fit for human consumption.

Thus, foods that were found in stores in China were poisonous. Fortunately, a solution to this problem has been found. The use of citrate ions prevents the accumulation of layers of gold thereby hindering the formation of melamine that prevent the formation of nanoparticles on the surface of gold. This process enables shielding continued reaction of the gold layers. When such interactions occur in food gold solution that causes coloration of food is formed. The particle size having effects on gold can also be determined through photography.

The size of gold particles ranges from 10 to 20 nm reflect light of different colors particularly red that turns to blue or purple if larger. Therefore, the chemical test for melamine can reveal varied collect chemical properties that can help in drawing conclusions. Usually, there is a color changes from red to blue when a solutions nitrate ions and gold particles are mixed. The significance of this chemical experiment lies in this interaction Procedure.Procedure: Take 0.2 mL of 100 mM gold salt stock solution and add 20 mL of distilled water to make 20 mL of 1mM gold salt solution.

Then take 20 mL of the 1mM NaAuCl4 and place it into 50mL beaker. Place the beaker and its content hot plate and stirred the mixture using a magnetic stir bar. Heat the solution until it boil. When the solution begins boiling, add 2 mL of 38.8 mM solution of trisodium citrate dehydrate (Na3C6H5O7.2H2O).The gold solution forms gradually as the citrate reduces the Au ions to the neutral gold atoms. Continue heating until full color change is observed (it should take about 30 minutes). After that, take 2 glass test tubes and added 5mL of distilled water in one test tube Then shined a laser light through each of these tubes.

Pour the 5ml of gold nanoparticles solution in a petri dish, and draw 0.5 mL of it in a syringe and filter through 0.02um filter. After that, open the filter across its seam by using a razor blade. Then take 2 glass test tubes and added 5mL of gold nanoparticle from part above to each test tube .after that we add 5mL of distilled water to each of these two test tubes. Use the dropper to add 5 to 10 drops of 0.5 M melamine solution to one of these two test tubes. Then pour this solution on a petri dish, draw 0.

5 mL of it in a syringe and filter through 0.02 um filter. Cut open the filter across its seam by using a razor blade.Results The experiment started with gold solution. The color of this gold solution was almost golden yellow. After the diluting, the solution the solution became colorless. On missing the gold solution with citrate solution and gold with nanoparticle, both solutions began to form a dark color that eventually became dark red. On passing laser light through nanoparticle, the solution filtered and the color turned to dark purple.

Introduction of the melamine solution into solution thickened the solution.Conclusion: The aim of this experiment was to determine whether there are traces of melamine in the food content. There results of the experiment indicated that the overall solution is dark purple in color. Through a lot of chemical process, the experiment finally revealed the final compound of the experiment. Materials:1) NaAuCl4.2H2O2) Na3C6H5O7.2H2O3) C3H6N6 9) Anotop 10 filters 4) Distilled water 10) 250 mL beakers5) Petri dishes 11) Razor blade 6) Test tubes 12) Test tube holder7) Pipettes and pipette gun 13) Laser pointer 8) Luer-Lok tm syringes