Chromatography Lab UPDATED ACTUAL
Exam Questions and CORRECT Answers
What were food color additives initially used for? - CORRECT ANSWER - To make food
more visually appealing to the consumer and mask poor quality.
Why were almost all of the original food color additives phased out? - CORRECT
ANSWER - Most were not safe for consumption and were being added to foods with no
health testing.
What could have been done to determine whether a color additive was harmful before it was
used in the food industry? - CORRECT ANSWER - They could have used
chromatography to determine the purity of each additive.
Of the original 695 color additives how many are still used today? - CORRECT
ANSWER -2
How many color additives total are used today? - CORRECT ANSWER -7
What do all approved food dyes share in common? - CORRECT ANSWER - They are
charged, water-soluble organic compounds that bind to natural ionic and polar sites in large food
molecules.
What is the difference between absorption and adsorption - CORRECT ANSWER -
Absorption is a physical and chemical event occurring during contact between materials that
have an attraction for each other. Adsorption is different from absorption in that the molecules of
the material physically adhere to the adsorbent rather than being absorbed into the interspaces of
the absorbent material.
What is chromatography used for? - CORRECT ANSWER - To separate organic
compounds for identification or purification.
, What are the two main components of chromatography? - CORRECT ANSWER -
Adsorbent & eluent
What is another name for the adsorbent? - CORRECT ANSWER - Stationary phase
(chromatography paper)
What is another name for the solvent or eluent? - CORRECT ANSWER - Mobile phase
What concept does chromatography work on? - CORRECT ANSWER - Compounds to be
separated are slightly soluble in the eluent and will spend some of the time in the eluent and
some of the time in the adsorbent.
What factors determine whether the separation by an eluent will be successful? - CORRECT
ANSWER - The affinity of a substance for the eluent versus the adsorbent allows
molecules to be separated by chromatography. (Depends on polarity)
How can you judge whether a mixture was separated properly by chromatography? - CORRECT
ANSWER - If you can clearly see all of the separate colors of a mixture and they have
practically stopped moving as the eluent continues to make its way up the paper.
Why does changing the polarity of the eluent affect the separation of a mixture so much? -
CORRECT ANSWER - Changing the polarity of the eluent will only slightly affect the
solubility of the molecules but may greatly change the relative attraction for the adsorbent.
What is capillary action? - CORRECT ANSWER - The ability of a liquid to flow against
gravity up a narrow tube or porous material.
Where do you put the eluent and carry out the separation? - CORRECT ANSWER -
Erlenmeyer flask
What is the most difficult task in chromatography? - CORRECT ANSWER - Choosing the
eluent is the most difficult task because the polarity determines the level of separation that will
Exam Questions and CORRECT Answers
What were food color additives initially used for? - CORRECT ANSWER - To make food
more visually appealing to the consumer and mask poor quality.
Why were almost all of the original food color additives phased out? - CORRECT
ANSWER - Most were not safe for consumption and were being added to foods with no
health testing.
What could have been done to determine whether a color additive was harmful before it was
used in the food industry? - CORRECT ANSWER - They could have used
chromatography to determine the purity of each additive.
Of the original 695 color additives how many are still used today? - CORRECT
ANSWER -2
How many color additives total are used today? - CORRECT ANSWER -7
What do all approved food dyes share in common? - CORRECT ANSWER - They are
charged, water-soluble organic compounds that bind to natural ionic and polar sites in large food
molecules.
What is the difference between absorption and adsorption - CORRECT ANSWER -
Absorption is a physical and chemical event occurring during contact between materials that
have an attraction for each other. Adsorption is different from absorption in that the molecules of
the material physically adhere to the adsorbent rather than being absorbed into the interspaces of
the absorbent material.
What is chromatography used for? - CORRECT ANSWER - To separate organic
compounds for identification or purification.
, What are the two main components of chromatography? - CORRECT ANSWER -
Adsorbent & eluent
What is another name for the adsorbent? - CORRECT ANSWER - Stationary phase
(chromatography paper)
What is another name for the solvent or eluent? - CORRECT ANSWER - Mobile phase
What concept does chromatography work on? - CORRECT ANSWER - Compounds to be
separated are slightly soluble in the eluent and will spend some of the time in the eluent and
some of the time in the adsorbent.
What factors determine whether the separation by an eluent will be successful? - CORRECT
ANSWER - The affinity of a substance for the eluent versus the adsorbent allows
molecules to be separated by chromatography. (Depends on polarity)
How can you judge whether a mixture was separated properly by chromatography? - CORRECT
ANSWER - If you can clearly see all of the separate colors of a mixture and they have
practically stopped moving as the eluent continues to make its way up the paper.
Why does changing the polarity of the eluent affect the separation of a mixture so much? -
CORRECT ANSWER - Changing the polarity of the eluent will only slightly affect the
solubility of the molecules but may greatly change the relative attraction for the adsorbent.
What is capillary action? - CORRECT ANSWER - The ability of a liquid to flow against
gravity up a narrow tube or porous material.
Where do you put the eluent and carry out the separation? - CORRECT ANSWER -
Erlenmeyer flask
What is the most difficult task in chromatography? - CORRECT ANSWER - Choosing the
eluent is the most difficult task because the polarity determines the level of separation that will
