Unit 2c write up
Unit 2 thin layer chromatography write-up
Abstract
Purpose of the experiment: the purpose of this experiment was to separate chemicals and
identifying which pigment is which on e. g carotene is yellow or orange and lutein is yellow, the
colors in the experiment helped to identify which color was what chemical The method used in
this experiment was a uniform thin plc strip with silica gel on it (TLC) at the end of this
experiment the colors separated and helped identify which color was the exact chemical ,and
the number of colors shows how many chemicals have been found .
Results
Introduction chromatography is a logical method which is used to separate colored chemicals
or substances out as the solvent moves up the paper it carries the mixture up with it, different
components of mixtures move up at different rates, chromatography has many uses in
medicine and industry. Everyday chromatography is used for food testing, drug testing, forensic
testing etc. There are different types of chromatography as substances have different polarities
but they have the same aim and always have a mobile phase and stationary phase.
In chromatography there are always two phases mobile phase and stationary phase the mobile
phase is aqueous /water based such as water or it can be nonaqueous carbon based such as
propane which is the chemical used in nail polish remover, in chromatography for every single
chemical used in the sample there's always a dynamic equilibrium between the two phases
which are mobile phase and stationary phase .
Two things which always affect the mobile phase to move which is solubility and adsorption the
more soluble a chemical is in its solvent the further it will travel if its less soluble it will travel
less further another factor that affect the mobile phase is its adsorption which means how
sticky a chemical is if its more adsorbing /more sticky it will travel less if its less adsorbing it will
travel more. Polarity has a huge effect on how attractive a chemical is to other substances.
Some molecules in chromatography have a slightly negative and a slightly positive charged
side the positive side goes towards the negative side of an different molecule because
opposites attract. The larger the charge difference, the more polar a molecule is.
,Thin layer chromatography
Thin layer chromatography is exactly as it says in the name – using a thin uniform layer of silica
gel onto a piece of glass or paper
Thin layer chromatography – as it says after the name thin layer of absorbent on the paper
absorbent is usually a uniform layer of silica gel which absorbs the materials the glass sheet is
handled with care as Environmental factors can contaminate it such as humidity or
temperature which could lead to false results and information
- Chromatogram is a graph representing the compounds
- Polar – molecules with uneven electrons distributions
- non-polar- molecules with even electron distributions
- Silica gel is the stationary phase
- Liquid solvent- mobile phase
Steps
- A pencil line is drawn at the bottom of the plate/tlc
- Small drop of the solution of the the mixture is placed on it in this case it was spinach
leave
- Show the original position of the drop using a pencil because if ink is used the ink would
also move along with the chromatogram
- When the spot is dry place, the plate stood in a solvent in a covered beaker
- As it travels 3 quarter of its way take it out and draw a line with a pencil where the liquid
ends
- Next, we measure the RF value
How does thin layer chromatography exactly work?
The stationary phase –silica gel in this case
Silica gel is a form of silicon dioxide – these silicon atoms are joined through oxygen atoms in a
giant covalent structure
- At the surface the silica gel you have SI-OH bonds
- https://www.chemguide.co.uk/analysis/chromatography/thinlayer.html
, -
- Structure of silica surface
-
The surface of the silica gel is polar because of the OH groups-form hydrogen bonds with
compounds around it as well as Van der Walla dispersion forces and dipole dipole attractions.
https://www.ausetute.com.au/tlc.html
Thin layer chromatography is mostly similar to paper chromatography however thin layer
chromatography is most of the time faster and it separates better because of its mobile phase
and stationary phase
- Stationary phase is the silica gel
- Mobile phase is how farther solvent travels up the TLC plate
- Components separate depending on their adsorption which basically means how sticky
or how far they travel
In thin layer chromatography how far a chemical travel depends on 2 things
- How soluble a chemical is in its mobile phase which relies on the attraction how much
attraction is present between the molecules of the chemical which is being separated
and of the solvent
- Adsorption – how sticky a chemical is to the stationary phase which is silica gel the more
adsorption which means the more stickier a chemical is it travels less further the less
adsorbing it is which means less stickier the chemical travels more further
- Chemical can only travel up the thin layer chromatography plate during the time when
its mixed in the solvent when its adsorbed onto the silica gel its stopped temporarily the
solvent move on without it this means the stronger a compound is adsorbed the less it
can travel along the tlc plate
Conditions Polar components Nonpolar components
Polar stationary phase Adsorbs strongly to the thin Adsorbs weakly to the
Nonpolar mobile phase layer chromatography paper its thin layer
less soluble in the solvent also chromatography paper
the spot travels a small distanceits more soluble in the
which also means the rf value is solvent and also the spot
shorter travels a larger distance
which means it has a
larger rf value
Nonpolar stationary phase Adsorbs weakly to the thin layer Adsorbs strongly to the
, Polar mobile phase chromatography paper its more thin layer
soluble in the solvent spot chromatography paper
travels furthest distance which its less soluble in the
means it has a higher rf value solvent travels small
distance which means
the rf value is also small
- You will find that as you increase the polarity of a solvent all the components of the
mixture move faster in the experiment(chromatography)
- https://youtu.be/ZCzgQXGz9Tg
- https://www.stuvia.com/en-gb/doc/2199659/btec-applied-science-unit-2-assignment-c-
chromatography
-
-
-
TLC – separating plant pigments
- Using thin layer chromatography to separate plant pigments ,we would use a combined
mobile phase of acetone as it provides much better results ,acetone is used by the
teacher as it's really dangerous if not handled carefully, this mobile phase separates the
pigments most clearly but downside of using thin layer chromatography to separate
plant pigments is that the distinction between each pigment is not as clear when a
solvent is used and it's really hard to visualize the separation and identify the colors
given to workout which color is which pigment is which
Advantages and disadvantages of thin layer chromatography
Advantages Disadvantages
Not really expensive Enviromental factors can be really difficult to
control such as wing and humidity which can
affect the accuracy of results
The process is quite simple doesn’t require Its qualitative not quantitate
much time and training
Only few equipment needed Tlc like pc –paper chromatography doesn't
have a long stationary phase which means
length of the separation is short/limited
Not much space/area required to carry out Can only separate chemicals that are
the practical dissolvable in the mobile phase
Paper chromatography- in paper chromatography the stationery phase is the paper – uniform
absorbent paper – and the mobile phase is the liquid solvent, first time paper chromatography
used in a way was to separate different dyes that make an particular ink-in paper
Unit 2 thin layer chromatography write-up
Abstract
Purpose of the experiment: the purpose of this experiment was to separate chemicals and
identifying which pigment is which on e. g carotene is yellow or orange and lutein is yellow, the
colors in the experiment helped to identify which color was what chemical The method used in
this experiment was a uniform thin plc strip with silica gel on it (TLC) at the end of this
experiment the colors separated and helped identify which color was the exact chemical ,and
the number of colors shows how many chemicals have been found .
Results
Introduction chromatography is a logical method which is used to separate colored chemicals
or substances out as the solvent moves up the paper it carries the mixture up with it, different
components of mixtures move up at different rates, chromatography has many uses in
medicine and industry. Everyday chromatography is used for food testing, drug testing, forensic
testing etc. There are different types of chromatography as substances have different polarities
but they have the same aim and always have a mobile phase and stationary phase.
In chromatography there are always two phases mobile phase and stationary phase the mobile
phase is aqueous /water based such as water or it can be nonaqueous carbon based such as
propane which is the chemical used in nail polish remover, in chromatography for every single
chemical used in the sample there's always a dynamic equilibrium between the two phases
which are mobile phase and stationary phase .
Two things which always affect the mobile phase to move which is solubility and adsorption the
more soluble a chemical is in its solvent the further it will travel if its less soluble it will travel
less further another factor that affect the mobile phase is its adsorption which means how
sticky a chemical is if its more adsorbing /more sticky it will travel less if its less adsorbing it will
travel more. Polarity has a huge effect on how attractive a chemical is to other substances.
Some molecules in chromatography have a slightly negative and a slightly positive charged
side the positive side goes towards the negative side of an different molecule because
opposites attract. The larger the charge difference, the more polar a molecule is.
,Thin layer chromatography
Thin layer chromatography is exactly as it says in the name – using a thin uniform layer of silica
gel onto a piece of glass or paper
Thin layer chromatography – as it says after the name thin layer of absorbent on the paper
absorbent is usually a uniform layer of silica gel which absorbs the materials the glass sheet is
handled with care as Environmental factors can contaminate it such as humidity or
temperature which could lead to false results and information
- Chromatogram is a graph representing the compounds
- Polar – molecules with uneven electrons distributions
- non-polar- molecules with even electron distributions
- Silica gel is the stationary phase
- Liquid solvent- mobile phase
Steps
- A pencil line is drawn at the bottom of the plate/tlc
- Small drop of the solution of the the mixture is placed on it in this case it was spinach
leave
- Show the original position of the drop using a pencil because if ink is used the ink would
also move along with the chromatogram
- When the spot is dry place, the plate stood in a solvent in a covered beaker
- As it travels 3 quarter of its way take it out and draw a line with a pencil where the liquid
ends
- Next, we measure the RF value
How does thin layer chromatography exactly work?
The stationary phase –silica gel in this case
Silica gel is a form of silicon dioxide – these silicon atoms are joined through oxygen atoms in a
giant covalent structure
- At the surface the silica gel you have SI-OH bonds
- https://www.chemguide.co.uk/analysis/chromatography/thinlayer.html
, -
- Structure of silica surface
-
The surface of the silica gel is polar because of the OH groups-form hydrogen bonds with
compounds around it as well as Van der Walla dispersion forces and dipole dipole attractions.
https://www.ausetute.com.au/tlc.html
Thin layer chromatography is mostly similar to paper chromatography however thin layer
chromatography is most of the time faster and it separates better because of its mobile phase
and stationary phase
- Stationary phase is the silica gel
- Mobile phase is how farther solvent travels up the TLC plate
- Components separate depending on their adsorption which basically means how sticky
or how far they travel
In thin layer chromatography how far a chemical travel depends on 2 things
- How soluble a chemical is in its mobile phase which relies on the attraction how much
attraction is present between the molecules of the chemical which is being separated
and of the solvent
- Adsorption – how sticky a chemical is to the stationary phase which is silica gel the more
adsorption which means the more stickier a chemical is it travels less further the less
adsorbing it is which means less stickier the chemical travels more further
- Chemical can only travel up the thin layer chromatography plate during the time when
its mixed in the solvent when its adsorbed onto the silica gel its stopped temporarily the
solvent move on without it this means the stronger a compound is adsorbed the less it
can travel along the tlc plate
Conditions Polar components Nonpolar components
Polar stationary phase Adsorbs strongly to the thin Adsorbs weakly to the
Nonpolar mobile phase layer chromatography paper its thin layer
less soluble in the solvent also chromatography paper
the spot travels a small distanceits more soluble in the
which also means the rf value is solvent and also the spot
shorter travels a larger distance
which means it has a
larger rf value
Nonpolar stationary phase Adsorbs weakly to the thin layer Adsorbs strongly to the
, Polar mobile phase chromatography paper its more thin layer
soluble in the solvent spot chromatography paper
travels furthest distance which its less soluble in the
means it has a higher rf value solvent travels small
distance which means
the rf value is also small
- You will find that as you increase the polarity of a solvent all the components of the
mixture move faster in the experiment(chromatography)
- https://youtu.be/ZCzgQXGz9Tg
- https://www.stuvia.com/en-gb/doc/2199659/btec-applied-science-unit-2-assignment-c-
chromatography
-
-
-
TLC – separating plant pigments
- Using thin layer chromatography to separate plant pigments ,we would use a combined
mobile phase of acetone as it provides much better results ,acetone is used by the
teacher as it's really dangerous if not handled carefully, this mobile phase separates the
pigments most clearly but downside of using thin layer chromatography to separate
plant pigments is that the distinction between each pigment is not as clear when a
solvent is used and it's really hard to visualize the separation and identify the colors
given to workout which color is which pigment is which
Advantages and disadvantages of thin layer chromatography
Advantages Disadvantages
Not really expensive Enviromental factors can be really difficult to
control such as wing and humidity which can
affect the accuracy of results
The process is quite simple doesn’t require Its qualitative not quantitate
much time and training
Only few equipment needed Tlc like pc –paper chromatography doesn't
have a long stationary phase which means
length of the separation is short/limited
Not much space/area required to carry out Can only separate chemicals that are
the practical dissolvable in the mobile phase
Paper chromatography- in paper chromatography the stationery phase is the paper – uniform
absorbent paper – and the mobile phase is the liquid solvent, first time paper chromatography
used in a way was to separate different dyes that make an particular ink-in paper
