Experiment 14 - lab report PDF

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Horaceena Findley ACHM125 Lenny B. 27 September 2017

Concentration of Red #40

Objective: Find the concentration of red dye #40 sample Hypothesis: The concentration range for the red #40 would be between 0.1-1.0 because the spectrophotometer has a linear absorbance range. The Beer-Lambert law helps determine the unknown concentration, which the graph from MicroLab gives the absorbance and wavelength. Using the beer lambert law equation, you can determine the concentration of the red #40. Furthermore, the graph from the MicroLab will record absorbance versus the wavelength, which is a linearly relationship. Concentration and absorbance are related because according to the beer lambert law, the concentration effects the absorbance. Therefore, if the concentration of the solution increases, then there are molecules that light can pass through. Variables: The independent variable in this experiment is the wavelength (nm) and the dependent variable is absorbance, which is affected by wavelength. Experimental Procedure: 1. Set up the MicroLab and measure the blank sample of pure water 2. Take a clean and dry vial for the experiment 3. Collect five dry, clean test tubes to fill with individual color dye solution 4. Label the first test tube containing 3 drops of the 2mM stock solution of the red #40 and the rest with water. 5. Pour a portion of the red #40 sample tube into the clean, dry spectrophotometer vial 6. Take the red #40 sample insert it in the sample holder, and then line up the marks on the vial 7. Repeat the previous steps with Blue #2 and Yellow #6 8. Add two drops of Red #40 and Blue #2 stock solution into the second clean tube and fill it with water

9. Pour some of the second test tube into the spectrophotometer vial dry with a Kimwipe on the outside. 10. Place the Blue #2 and Red #40 spectrophotometer vial onto a sample holder and line the marks on the vial 11. Repeat the process for the combination of Blue#2 and Yellow #6 12. Put 2 drops of Blue #2 solution into a clean, dry 50 mL Erlenmeyer flask 13. Dilute the Blue#2 solution in the flask with approximately 10 ml of water 14. Pour 5.0M of NaOH to the diluted solution a drop at a time and gently swirl 15. Transfer solution a portion into a clean and dry spectrophotometer vial when the color changes 16. Wipe the spectrophotometer vial with a Kimwipe on the outside 17. Place the sample into the sample holder and watch the mark line up on your vial 18. Dipose solution containing 5.0 M NaOH solution into the waste container 19. Measure several different food dye solution’s absorbance spectrums by using the MicroLab Spectrophotometer. 20. Key Math Equations: Transmittance (T) = I/I0 Absorbance equation: A = e * I * c Chemical Hazards: Must wear safety goggle. Nitrile gloves, and lab coat throughout the entire experiment to avoid chemicals interacting with your skin and eyes. Be cautious of the NaOH it can cause severe burns so, be careful handling it and when done it must be removed into the waste container with the label, NaOH waste. For the rest of the solution obtaining the dye solution can be poured down the drain. Clean up the station where the experiment was conducted....