Determining The Synthesis Of DCPIP

Background Information: Spectrophotometry is a method that measures how much light is absorbed by using the electromagnetic spectrum. By seeing which colors are absorbed and which are reflected scientists can determine what a substance is without having to touch them. This is possible because each substance has a specific absorbance spectrum, meaning that the absorption spectrum of two different substances cannot be the same.
Purpose/Hypothesis:
1. The purpose of the experiment was to determine the extinction coefficient for a solution of DCPIP. This was done by using the concentration, absorbance, wavelength values.
2. The purpose of the experiment was to determine the concentration of an unknown DCPIP sample by measuring the absorbance maximum of a specific concentration of DCPIP.
3. There was no hypothesis. We were merely trying to replicate the experiment.
Procedure:
Once labeled we obtained DI water and placed it into a properly labeled beaker. Next we placed approximately 15 ml of stock1mM DCPIP into another labeled flask and began diluting. The DCPIP was diluted to 0.1mM by adding 10ml of 1mM DCPIP to 90ml of distilled water. Then we added about 5 ml of the 0.1mM DCPIP solution to a clean spectorophometer tube, remembering that a blank was also needed we added 5ml of distilled water to another spectorphometer tube. After setting the spectrophometer to 500nm we placed zero and blank the spectrophometer, later adding the tube containing the 0.1mM of DCPIP recorded the results. Once the results were recorded we took out the tube of DCPIP solution and the repeated the process 20 more times each time increasing the wavelength by 10nm. Subsequently after all of the absorbance was recorded we determined that the maximum absorbance wavelength was 600nm because it had the highest absorbance