Results 1. Determine Maximum Absorption for Bromophenol Blue Wavelength 425 450 475 500 525 550 575 600 625 Absorbance a. What is the wavelength of maximum absorbance for bromophenol blue? b. What color is this? 2. Standard Curve for Bromophenol Blue Tube Number 1 2 3 4 5 6 7 8 9 Concentration Absorbance Units 3. Determination of an Unknown Unknown Letter: _______________ Absorbance Value: ______________ Conclusions 1. Describe the relationship between absorbance and the concentration of a light-absorbing substance in a solution. 2. Explain how standard curves can be used to determine the concentration of a substance in a solution. 3. You have a solution that appears green. What color light is/are being transmitted? Absorbed? 4. What is the purpose of a blank when using a spectrophotometer? 5. You are making a standard to be used to measure protein concentration. You have added 2 ml of protein, 3 ml of water, and 4 ml of an indicator dye. How would you prepare the blank for this experiment? 6. To a test tube you add 3 ml of a stock 0.05 mg/ml dye and 7 ml of water. What is the final concentration of dye in this tube? 7. What is the concentration of bromephenol blue in your unknown sample?