Chemistry – Experimental techniques and chemical analysis - Chromatography | e-Consult
Experimental techniques and chemical analysis - Chromatography (1 questions)
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Answer:
To identify substances A and B, we need to compare their Rf values to the Rf values of the known substances (aniline and benzene). The Rf value is calculated as (distance travelled by the substance) / (distance travelled by the solvent).
From the chromatogram, substance A has an Rf value of approximately 0.65 and substance B has an Rf value of approximately 0.40.
Aniline has an Rf value of 0.55 and benzene has an Rf value of 0.30. Therefore:
- Substance A has an Rf value of 0.65, which is closer to the Rf value of aniline (0.55) than to benzene (0.30). Therefore, substance A is likely to be aniline.
- Substance B has an Rf value of 0.40, which is closer to the Rf value of benzene (0.30) than to aniline (0.55). Therefore, substance B is likely to be benzene.
Reasoning: Substances with similar chemical properties will travel the same distance on the chromatography paper because they interact with the stationary phase (paper) and the mobile phase (solvent) in a similar way. Therefore, substances with similar Rf values are likely to be the same.