TECHNICAL AND THEORETICAL SKILLS
In this assignment you will
prepare volumetric solutions
carry out a serial dilution procedure
determine the extinction coefficient of a compound
monitor the rate of a chemical react
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TECHNICAL AND THEORETICAL SKILLS
In this assignment you will
prepare volumetric solutions
carry out a serial dilution procedure
determine the extinction coefficient of a compound
monitor the rate of a chemical reaction
use a spreadsheet to analyze data
calculate the order and rate constant of a reaction
SAFETY
FD&C Red #3, or Erythrocin B sodium, the food coloring dye that you will use in this
experiment is intensely colored. Always wear safety glasses or goggles and a protective lab coat
or apron. Handle the dye carefully avoiding spilling on the balance or bench top. Sodium
hypochlorite, household bleach, is a bronchial irritant. Keep solutions covered or in the hood;
avoid breathing the vapors. Immediately, wipe any spills of either reagent and wash any residues
with large quantities of water.
INTRODUCTION
In this assignment, you will prepare a solution of FD&C Red #3 (Red #3) and study its rate of
reaction with sodium hypochlorite. Since this reaction is very visible, you will use a
spectrophotometer to quantitatively follow the rate of disappearance of the colored reagent.
Your rate data will allow you to determine the rate law and to propose a possible mechanism for
the reaction.
FD&C #3
Because of the extended conjugation of alternating double bonds within the molecule, the π−π*
absorption occurs in the visible region of the spectrum at 530 nm. When the dye reacts with
hypochlorite, the color disappears. Even though the product of this reaction has never been
determined, we can carry out rate studies with the reagents to determine the mechanism that
occurs. One possible explanation for this reaction is that the bleach oxidizes the central
methylene carbon so that the molecule no longer has the extended conjugation system and the
π−π* absorption of the less conjugated product occurs at a lower wavelength outside of the
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