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Difficulty: EasyPure and Impure Substances and Criteria of Purity

A pure chemical compound analyzed using thin-layer or paper chromatography under standard conditions produces a single distinct spot on the developed chromatogram.

Answer: Answer

Answer

The statement is true because pure substances contain only one component and yield a single spot during chromatographic separation.
A fundamental criterion of chemical purity is that a pure substance gives a single spot on a chromatogram, as it contains no additional chemical species to separate out.

Step-by-Step Solution

1
Identify the core principle of chromatography as a test of purity.
Chromatography separates components of a sample based on their relative affinities for the stationary and mobile phases.
Understanding how chromatography separates substances helps evaluate purity criteria.
2
Relate component count to the number of spots observed.
A pure compound contains only one chemical species, so it does not separate into multiple components and produces a single spot.
The appearance of more than one spot signifies a mixture containing impurities.

Key Concept

Single spot on a chromatogram as a criterion of chemical purity
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Topics

Pure and Impure Substances and Criteria of Purity