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Litmus

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Also Known AsLitmus indicator, litmus paper, litmus solution, azolitmin (main active component)

What is Litmus?

A natural acid-base indicator derived from lichens that turns red in acidic conditions and blue in basic conditions. Litmus paper (red and blue) is widely used for quick pH testing. While imprecise compared to pH meters, it remains a useful qualitative tool.

Properties & Characteristics

Litmus is a natural pH indicator extracted from lichens (primarily Roccella tinctoria). It is a mixture of chromophoric anthocyanin compounds. In acidic solution (pH < ~6), litmus is red; in basic solution (pH > ~8), it is blue; at neutral pH (~7), it is purple. Litmus paper (red and blue) is used for rough qualitative pH testing. Litmus is not suitable for accurate titrations (wide transition range, ~pH 5-8) but remains a classic qualitative indicator.

Uses & Applications

Litmus is used in: educational demonstrations of acid-base chemistry, qualitative testing of solutions (acid, base, or neutral), testing of gases (moistened litmus paper turns red with HCl, blue with NH₃), and as a historical reagent in qualitative analysis.

Safety Information

Litmus solution is essentially non-toxic (from natural lichen source). The solutions used to prepare litmus paper may contain dilute acid or base. No specific hazard beyond standard laboratory chemical handling.

Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.

Key Facts

Term Litmus
Synonyms Litmus indicator, litmus paper, litmus solution, azolitmin (main active component)

Frequently Asked Questions

A natural acid-base indicator derived from lichens that turns red in acidic conditions and blue in basic conditions. Litmus paper (red and blue) is widely used for quick pH testing. While imprecise compared to pH meters, it remains a useful qualitative tool.

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