Food Dye Spectroscopy - Planning Document Part 1 copy

Food Dye Spectroscopy New project, new roles! Team Leader Recorder Communicator Safety Officer Swetha Jagannathan Sara Sherman Elizabeth Smith Audrey Molnar Planning Questions (Part 1) 1. There are two scales on the spectrometer: absorbance and transmittance. a. What does absorbance measure? The quantity of light absorbed by your sample. b. What does transmittance measure? The amount of light that passes through a material and is usually reported as a percent comparing the light energy transmitted throuhg through a material to the light energy that entered the material. c. What is the relationship between the two? Absorbance = 2 – log(%T). They are inversely proportional. d. Which will you measure? Absorption 2. You will need to write a procedure that uses the standard FD&C dye solutions to determine the relationship between the wavelength of light absorbed and the color you see (Week 1, Goal 1). a. How will you make your solutions? For example, how would you make a solution that contains 25% of the standard dye solution in water? Be sure to include sample calculations in the Mathematical Equations section of the planning document. To make a 25 percent solution you could have 2.5mL of 100% concentration and 7.5 mL of water to get 10mL of solution at 25%. 75 mL of water and dilute 25mL of the liquid dye into the water to make 100mL of overall liquid. b. At what wavelengths should you take readings to obtain absorption spectra in the visible region of the electromagnetic spectrum? 380 to 700 nanometers c. If your solution is too strong or too weak to give accurate readings, what will you do to get better results? Change the concentration of dye 3. You will need to write a procedure that uses one of the food dyes to determine the relationship between concentration and the amount of light absorbed (Week 2, Goal 3). a. Which wavelength of light will you use to investigate this effect for the dye that you selected? ( Hint: Which wavelength do you think will give the best results? ) b. The wavelength of light that we will be using to investigate is lambda max. c. Why did you choose this wavelength? I chose this because it is the max amount of absorbance that can be passed through the sample. d. Select at least four (4) concentrations (other than 25%) for your measurements expressed as percent of standard dye solution in water. 20%,40%,60%,80% e. Each member of the team should calculate the volume of dye solution and volume of water needed to prepare one of the four (4) solution concentrations chosen. - 2mL of 100% concentration and 8mL of water = 10mL of solution at 20%

- 4mL of 100% concentration and 6mL of water = 10 mL of solution at 4 0% -6mL of 100% concentration and 4mL of water = 10mL of solution at 60% -8mL of 100%concentration and 2mL of water = 10mL of solution at 80% 4. Describe how you will determine the relationship between the concentration of the dye solution and the amount of light absorbed. a. Identify the two variables in these measurements. Which is the cause, and which is the effect? The concentration is the independent variable and the amount of light absorbed is the dependent variable b. How could you determine if there is a mathematical relationship between the absorbance and the concentration? What methods do you know that might reveal such a relationship? P lot them on a graph and find the trend line. Since the relationship should be directly proportional, the trend line should show a positive trend with the y-intercept being 0 or close to 0. Chemicals (add rows as needed) Chemical Name Important Safety Information The 7 FD&C food dyes. Waste Management Disposal Method Chemical(s) That Should Be Disposed By This Method Sink water All food dyes Trash can Waste carboy Food dye Other (specify) Equipment  SpectroVis + spectrophotometer  W ater  FD&C Blue #1  FD&C Blue #2  FD&C Green #3  FD&C Yellow #5  FD&C Yellow #6  FD&C Red #3  FD &C Red #40

experiments they would perform. Each team member's plan should have sufficient detail to allow members of the team to switch responsibilities and still know what to do. Sara will determine the relationship between the amount of light absorbed with 20% concentration of each dye and will repeat for all seven dyes. I will place concentration into the vessel and set up the machience for use . I will write down lamba max based off the graph shown on the spectrophotometer . Liz will make a 60 percent food dye solution by mixing 4 ml of water with 6 ml of food dye. To prime the spectrophotometer, I would place the water into the vessel and set the machine up for use. I will write down the lambda max based off the graph shown on the spectrophotometer. Swetha will make a 40% solution by mixing 4 mL of food dye with 6 mL of water. Using the spectrophotometer that is primed with water , she will measure the absorbance of the solution and write down the lambda max based on the graph shown. Audrey will make an 80% solution by mixing 8mL of the dye with 2mL of the water. Using the spectrophotometer she will observe and record the length of the wavelengths and will repeat for each color of dye.