What 2 distances are important when calculating Rf values in chromatography?1Distance travelled by 2Distance travelled by solvent
Question
What 2 distances are important when calculating Rf values in chromatography?1Distance travelled by 2Distance travelled by solvent
Solution
The two distances that are important when calculating Rf values in chromatography are:
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Distance travelled by the solute (the substance being separated): This is the distance from the origin (where the sample was initially applied) to the center of the spot where the solute ended up.
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Distance travelled by the solvent (the substance used to move the solute): This is the distance from the origin to the final level reached by the solvent.
The Rf value (Retention Factor) is then calculated by dividing the distance travelled by the solute by the distance travelled by the solvent. This value helps to identify the solute, as each compound has a characteristic Rf value under specific conditions.
Similar Questions
A student used paper chromatography to separate two components, I and II, in a solution. A spot of the solution was initially placed at the origin.The distances measured by the student on the chromatogram are shown in the table below. DistanceSolvent front7.5 cmComponent I6.0 cmComponent II1.5 cm behind Component I The Rf value of component II is closest toa.0.25b.0.20c.0.60d.0.80
14.Calculate the Rf value when one colour had moved by 50mm and the solvent had moved by 100mm. Calculate to 1 decimal place.
What is chromatography used to separate?An insoluble solid from a liquidTwo or more liquids with different boiling pointsDifferent substances dissolved in a liquidTwo or more different gases2Which of the following statements about paper chromatography is not true?Less soluble substances travel further up the paperSubstances are separated based on how attracted they are to each phaseThe stationary phase is the paperThe mobile phase is the solvent3What are Rf values useful for?To determine how much solvent to use in the chromatography procedureTo calculate how much paper to useTo identify unknown samples by comparing them with known samplesTo determine the number of different substances in a solvent4How is the Rf value of a substance calculated?Distance moved by substance divided by distance moved by solventDistance moved by solvent minus distance moved by substanceDistance moved by solvent divided by distance moved by substanceDistance moved by substance multiplied by distance moved by solvent5In the core practical ‘Paper chromatography to investigate the composition of ink’, a line is drawn at the bottom of the paper onto which spots of known ink colourings plus an unknown sample are placed. There are several key points to remember when setting up this practical. Which of the following is incorrect? The line must be above the water levelThe line must be in penThe sides of the paper must not touch the beakerThe sample spots should not spread out too far6On a paper chromatogram only one spot is produced. What does this tell you? The paper was not large enoughThe substance being separated is an impure substanceToo much solvent was usedThe substance being separated is a pure substance
What is one of the advantages of carrying out chromatography?only coloured substances can be used for the experimentonly small amount of the sample is neededonly applicable to substances which are soluble in the solventcan only work on paper materials to form the chromatogram
Which is not a development technique of paper Chromatography ?a.Ascendingb.Circularc.Horizontald.Two dimensional
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