Lab 7 Column Chromatography CHEM250L
Student Name:Access Code (located on the lid of your lab kit): A9F7-K3Q2-M8L4-D6
Lab Report Format Expectations
Utilize college level grammar and professional formatting when completing this worksheet.
All drawings must be clear and presented in high resolution photos with your handwritten name clearly
visible in the background.
Pre-Lab Questions
1. In this lab, you will conduct two experiments. Explain both of these experimental methods
below in your own words. Clearly delineate between the two methods, how they are
conducted, and what chemical properties each can reveal. (Hint: Your response should be at
least 5-6 sentences in length.)
In this lab, two experimental methods are used: chromatographic separation and spectrophotometric
analysis. In the first method, chromatography is used to separate the different dyes present in grape
soda based on their relative affinities for the stationary and mobile phases. Components that interact
more strongly with the mobile phase travel faster, while those that interact more strongly with the
stationary phase move more slowly.
In the second method, spectrophotometry is used to determine the concentration of each dye by
measuring how much light the dye absorbs at a specific wavelength. By applying Beer–Lambert Law,
absorbance values are related directly to concentration. Together, these methods allow both physical
separation and quantitative analysis of the dyes present.
, Lab 7 Column Chromatography CHEM250L
EXERCISE 1: SEPARATING THE DYES IN GRAPE SODA
Introduction Questions
1. Explain, generally, how this method separates the dyes in this experiment. (Hint: Include
a discussion of the factors that affect the rate at which the dyes move.)
This method separates dyes based on differences in polarity and intermolecular interactions
with the stationary and mobile phases. As the solvent moves through the stationary phase, dyes
that are more soluble in the mobile phase move faster, while those with stronger attraction to
the stationary phase move more slowly. Molecular size and polarity affect the rate of
movement, resulting in visible separation of colors.
2. Why were water and isopropanol chosen for the mobile phase?
Water and isopropanol were chosen because they provide a mobile phase with intermediate
polarity that can dissolve the dyes while still allowing differences in dye mobility. The mixed
solvent system improves separation efficiency compared to using water alone.
3. Why is Step 46 important in the procedure?
Step 46 is important because it ensures that fractions are collected at the correct time,
preventing overlap between dyes. Proper timing ensures better separation and more accurate
downstream concentration analysis.
Student Name:Access Code (located on the lid of your lab kit): A9F7-K3Q2-M8L4-D6
Lab Report Format Expectations
Utilize college level grammar and professional formatting when completing this worksheet.
All drawings must be clear and presented in high resolution photos with your handwritten name clearly
visible in the background.
Pre-Lab Questions
1. In this lab, you will conduct two experiments. Explain both of these experimental methods
below in your own words. Clearly delineate between the two methods, how they are
conducted, and what chemical properties each can reveal. (Hint: Your response should be at
least 5-6 sentences in length.)
In this lab, two experimental methods are used: chromatographic separation and spectrophotometric
analysis. In the first method, chromatography is used to separate the different dyes present in grape
soda based on their relative affinities for the stationary and mobile phases. Components that interact
more strongly with the mobile phase travel faster, while those that interact more strongly with the
stationary phase move more slowly.
In the second method, spectrophotometry is used to determine the concentration of each dye by
measuring how much light the dye absorbs at a specific wavelength. By applying Beer–Lambert Law,
absorbance values are related directly to concentration. Together, these methods allow both physical
separation and quantitative analysis of the dyes present.
, Lab 7 Column Chromatography CHEM250L
EXERCISE 1: SEPARATING THE DYES IN GRAPE SODA
Introduction Questions
1. Explain, generally, how this method separates the dyes in this experiment. (Hint: Include
a discussion of the factors that affect the rate at which the dyes move.)
This method separates dyes based on differences in polarity and intermolecular interactions
with the stationary and mobile phases. As the solvent moves through the stationary phase, dyes
that are more soluble in the mobile phase move faster, while those with stronger attraction to
the stationary phase move more slowly. Molecular size and polarity affect the rate of
movement, resulting in visible separation of colors.
2. Why were water and isopropanol chosen for the mobile phase?
Water and isopropanol were chosen because they provide a mobile phase with intermediate
polarity that can dissolve the dyes while still allowing differences in dye mobility. The mixed
solvent system improves separation efficiency compared to using water alone.
3. Why is Step 46 important in the procedure?
Step 46 is important because it ensures that fractions are collected at the correct time,
preventing overlap between dyes. Proper timing ensures better separation and more accurate
downstream concentration analysis.
