0
Response Details:
1) factor that affects the Rf value of TLC is the polarity of the solvent. If the solvent is too polar all of the compounds can run right up the plate resulting in poor separation.
2) The RF value is used to established the identity of the spots of TLC plate.
3) The RF value is ratio of the distance the solvent travels to the distance compound travels.
4) The factors can affect RF values. The absorbent uniformity on the thin layer plate, same concentration(spotting is too weak or strong), room temperature during the mobile phase and development distance of the solvent during the mobile phase can all affect the results.
5) Multiple solvent system are necessory when utilizing TLC for identification purposes.Response Details:
1) factor that affects the Rf value of TLC is the polarity of the solvent. If the solvent is too polar all of the compounds can run right up the plate resulting in poor separation.
2) The RF value is used to established the identity of the spots of TLC plate.
3) The RF value is ratio of the distance the solvent travels to the distance compound travels.
4) The factors can affect RF values. The absorbent uniformity on the thin layer plate, same concentration(spotting is too weak or strong), room temperature during the mobile phase and development distance of the solvent during the mobile phase can all affect the results.
5) Multiple solvent system are necessory when utilizing TLC for identification purposes.
Wiki User
∙ 15y ago
Add your answer:
Earn +20 pts
Why Ni positive 2 and iron positive 3 ions have different Rf values?
Rf values are determined by the polarity of the substance tested. Even though these atoms may have similar electron configuration, it is not identical, and neither are their Rf values.
How would you expect Rf values to change if you went from hexane-ethyl acetate solvent system to ethyl acetate only?
the rf values would increase
How you might use Rf values to identify an unknown substance?
Although Rf values technically remain constant if the following are held constant: * solvent system * adsorbent * thickness of the adsorbent * amount of material spotted * temperature They are generally not used to identify an unknown substance specifically, since these factors are sometimes difficult to control. Most generally, during a chromatography experiment an unknown sample can be compared directly to a known sample simultaneously, i.e. they will have similar Rf values.
A compound has a very high Rf value in a polar solvent what can you say about its molecular structure?
Rf Value - It tells you the affinity that the compound has to the solvent...High Rf = little or no polar groups and low Rf = more polar groups. Question: In TLC (thin-layer chromatography) when the compound has a high Rf the solvent is: a. less polar b. Is more polar Answer: a. less polar
You run a TLC plate spotted with three compounds naphthalene o-toulic acid and fluorenol. Predict the relative Rf values?
You'd have to know which mobile phase is used before you can make a guess at the Rf values. It might be quite hard to find a decent mobile phase to have all those compounts running, naphtalene and fluorenol are bulky and have low affinity for the polar silica, where as o-toluic acid will stick to the bottom of the plate due the COOH group.
Arrange the following compounds in order of increasing Rf values in TLC Anthracene benzil tryphenylmethanol?
The order of increasing RF values in TLC is Benzil, methanol anthracene and tryphenyl.
Why is that the centre of the spot is considered when calculating Rf values for TLC?
outside are jus impurities
If two samples have identical Rf values does this mean they are identical molecules?
Rf is a value that is usually seen in chromatography (such as thin-layer chromatography, or TLC). It is a measure of how far the compound has traveled along the stationary phase. This distance is affected by the compounds affinity to the stationary phase (the TLC plate) and its affinity to the mobile phase (the solvent). Generally this directly relates to the polarity of the compound, but other factors may influence this.Since similar compounds (in structure) also have similar dipole moments (polarity), similar compounds will typically have similar Rf values. However, there are exceptions and compounds that have different functional groups can end up having similar polarities and thus similar Rf values. TLC is usually used as an initial measure of identification. If the Rf of the reference matches the Rf of the unknown, it is likely the compounds are the same, but further investigation with other analytical techniques is necessary to confirm this.
What is the RF value for paracetamol?
That depends on many factors including the elution solvent used, the type of TLC plate used, etc.. When using .5% of acetic acid in ethyl acetate as your elution solvent and on a plastic backed plate, the Rf-value should be around 79.82%
Why are Rf values used?
Rf values are used mainly for simplicity. These values are generally easier to use to obtain percentages between a couple objects instead of using values that are already established.
Why Ni positive 2 and iron positive 3 ions have different Rf values?
Rf values are determined by the polarity of the substance tested. Even though these atoms may have similar electron configuration, it is not identical, and neither are their Rf values.
How are Rf values used in real life?
Rf values can be used to identify the type of drugs that had been taken by those who went through drug overdose.
How would you expect Rf values to change if you went from hexane-ethyl acetate solvent system to ethyl acetate only?
the rf values would increase
Will acetaminophen or ibuprofen have a higher Rf if you carry out a TLC separation of on a silica gel using a non-polar developing solvent?
Acetaminophen will have Rf value of about 0.4 and ibuprofen will have Rf value of about 0.6 if the non polar solvent used is ethanol.
What are the significance of values?
Rf Values determine the solubility of a substance with respect to a certain solvent.
How you might use Rf values to identify an unknown substance?
Although Rf values technically remain constant if the following are held constant: * solvent system * adsorbent * thickness of the adsorbent * amount of material spotted * temperature They are generally not used to identify an unknown substance specifically, since these factors are sometimes difficult to control. Most generally, during a chromatography experiment an unknown sample can be compared directly to a known sample simultaneously, i.e. they will have similar Rf values.
What is the RF value for aspirin using TLC?
Rf value changes with every experiences..... it depends on what was your solvant, the room température, the chromatograph you used..... that's why you wont find Rf tables in organic chemistry books
