Red Dye Concentration Experiment

Summary
Determining the concentration of a liquid can be a tricky process involving complex procedures if it were not for science’s ability to test a substance’s absorbency through spectrophotometry. The experiment was carried out to discover the concentration of Red Dye #40 in several common soft drinks. The samples of the dye were diluted, and tested using a spectrophotometer. The absorbencies of these samples were then recorded, and a standard line curve with the concentration equation and R2 value was created with these results. Using the absorbencies of the dye samples, the concentrations of the soda samples were determined using the slope equation provided by the graphing software. The hypothesis that the more intense color of red stock

All the test tubes contained in total 3 mL of solution. The following solutions’ concentrations in a tube were .1 mL of dye and 2.9 mL of water, .25 mL of dye and 2.75 mL of water, .5 mL of dye and 2.5 mL of water, 1.0 mL of dye and 2.0 mL of water, 2.0 mL of dye and 1.0 mL of water, and 3.0 mL of dye and 0 mL of water. These samples were tested by the spectrophotometer, and the absorbencies recorded. This whole process was completed twice and the absorbencies were averaged. Lastly, final concentrations and dilution factors were calculated by using the appropriate formulas.
The final portion of the lab consisted of creating a lined scatterplot in Microsoft Excel with the absorbencies from the standard curve data chart. The chart was created to display the linear trendline, R-squared value, and slope equation. Then four sodas, Big Red, Big K Grape Soda, Faygo Red Pop, and Cherry 7 Up and one unknown sample containing red dye were processed through the absorbency tests, and diluted if necessary in a 1:1 or 1:3 ratio of water to soda. Using the equation determined from the standard curve graph, the concentrations of Red dye #40 was calculated for the sodas and the unknown liquid