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2024-04-22T05:25:38Z

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[[File:Lackmus.jpg|Lackmus|thumb]] [[File:7-hydroxyphenoxazone.svg|7-hydroxyphenoxazone|thumb|left]] [[File:Parmelia_sulcata.jpeg|Parmelia sulcata|thumb|left]] [[File:Litmus_paper.JPG|Litmus paper|thumb]] '''Litmus''' is a [[water-soluble]] mixture of different [[dye]]s extracted from [[lichen]]s, primarily [[Roccella tinctoria]]. It is often absorbed onto [[filter paper]] to produce one of the oldest forms of [[pH indicator]], used to test materials for [[acidity]] or [[alkalinity]].

==History==
The use of litmus is thought to date back to the 1300s, although the exact origins are unclear. It was first used in [[Europe]] after being introduced by the [[Arab]]s, who had discovered its properties through their interest in [[alchemy]] and [[chemistry]]. The name "litmus" comes from an Old Norse word meaning "to dye" or "to color."

==Production==
Litmus is made through a complex process that involves fermenting the lichens with [[potassium carbonate]], [[ammonia]], and various other compounds over several weeks. This fermentation process leads to the formation of the litmus mixture, which contains around 10-15 different dyes. These dyes are primarily of the [[anthraquinone]] family, which are known for their pH-sensitive color changes.

==Chemical Properties==
Litmus is a [[pH indicator]] that changes color in response to the acidity or alkalinity of a solution. When added to an acidic solution (pH < 7), litmus turns red, and when added to an alkaline solution (pH > 7), it turns blue. The transition range of litmus is approximately between pH 4.5 and 8.3. However, it is most accurate around the neutral range (pH 7).

==Uses==
Litmus paper, which is paper treated with litmus dye, is commonly used in educational settings and laboratories to quickly assess the pH level of a solution. It is particularly useful in [[chemistry]] and [[biology]] labs for performing simple acid-base titrations or for testing the pH of various substances. Despite the development of more precise methods of pH measurement, such as [[pH meters]], litmus paper remains popular due to its simplicity and ease of use.

==Limitations==
While litmus paper is a convenient tool for indicating pH, it has limitations. It does not provide an exact pH value, only a rough indication of whether a solution is acidic or alkaline. Additionally, the color change can be subjective and may be influenced by the lighting conditions or the presence of other colored substances in the solution.

==Conclusion==
Litmus remains an essential tool in the field of chemistry and education for the simple and rapid assessment of the acidity or alkalinity of a solution. Its ease of use, affordability, and the immediate visual feedback it provides make it an enduring choice for basic pH testing.

[[Category:Chemical substances]]
[[Category:PH indicators]]

{{chemistry-stub}}

Litmus - Revision history

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