RF Measurement: Do I Need a Unit?

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SUMMARY

In RF measurement, the Rf value is a ratio and does not have units. It is calculated by dividing the distance traveled by the compound by the distance traveled by the solvent, both measured in centimeters, resulting in a unitless value. For column chromatography, Rf can be interpreted as the "fraction of column volume," indicating that an Rf of 0.5 means the compound travels half the length of the column when one column volume of eluent is used.

PREREQUISITES
  • Understanding of Thin Layer Chromatography (TLC)
  • Familiarity with column chromatography techniques
  • Basic knowledge of ratios and unit cancellation
  • Ability to measure distances accurately in centimeters
NEXT STEPS
  • Research Thin Layer Chromatography (TLC) techniques and applications
  • Learn about column chromatography and its operational principles
  • Study the concept of Rf values in various chromatography methods
  • Explore the significance of solvent front in chromatographic separations
USEFUL FOR

Chemists, laboratory technicians, and students involved in chromatography and separation techniques will benefit from this discussion.

MercuryRising
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just a simple question, do Rf have a unit?
i'm measuring in cm, so do i use cm as unit for Rf or do just leave it blank?
 
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Rf is a ratio, so it won't have any units. If your compound travels half as far up the TLC plate as you solvent, you find the Rf by dividing the two distance (measured in cm), so the units cancel, and you get 0.5.

For column chromatography, I find it useful to think of Rf as "fraction of column volume." So an Rf of 0.5 means that when you push through one column volume of eluent, your compound will travel one half the length of the column.
 
thanks, i get it now :biggrin:
 

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