1-What are the basic/general principles of chromatography, and how are stationar
ID: 1009039 • Letter: 1
Question
1-What are the basic/general principles of chromatography, and how are stationary and mobile phases involved in the separation of compounds?
2-What are the specifics of TLC as a chromatographic method?
3- What is an Rf value and how is this used in TLC?
4-Is ethyl acetate polar or non-polar? How does the solvent polarity (or lack thereof) compare to the silica plate?
5-Given your four known standards (caffeine, Aspirin, Acetaminophen, Ibuprofen) and based on their structures and functional groups, what can you say about their relative polarity and size?
Explanation / Answer
1-What are the basic/general principles of chromatography, and how are stationary and mobile phases involved in the separation of compounds?
Chromatography, is a analytical method to separate the mixture into compounds.
This is based on differential strength of adhesion of the various elements of the analyte towards the stationary and mobile phase.
As the results of this the separation of the components will possible.
2-What are the specifics of TLC as a chromatographic method?
TLC means Thin-layer chromatography (TLC)
It is a type of chromatography technique which is used to separate non-volatile mixtures.
TLC is worked on a sheet of glass, plastic, or aluminum foil, which is coated with a thin layer of adsorbent material, like silica gel, aluminium oxide (alumina), or cellulose.
Here this layer works as adsorbent and called stationary phase while the solvent is mobile phase.
3- What is an Rf value and how is this used in TLC?
Rf = distance moved by the compound or spot / distance moved by the solvent.
By the calculating the Rf values we can identified compound.
The more polar a compound has the lower Rf value. Because Polar compound want to bond with polar silica, while non-polar compound will move fast with eleuent hence this non-polar has highest Rf value.
4-Is ethyl acetate polar or non-polar? How does the solvent polarity (or lack thereof) compare to the silica plate?
Yes, ethyl acetate polar solvent
The more polar a compound has the lower Rf value means it is compound B. Because Polar compound want to bond with polar silica, while non-polar compound will move fast with eleuent hence this non-polar has highest Rf value.
The Rf values becomes larger if a more polar solvent (like ethyl acetate) were used in place ligroin. Polar solvent is more proficient at eluting the compounds from the polar adsorbent hence every compound of mixture moves faster, so the distance moved by the compound is becomes larger thus each compound would have a larger Rf value .
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