Litmus

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Litmus is a water soluble mixture of different dyes extracted from lichens. Litmus absorbed onto filter papers is one of the oldest and most known form of pH indicator.

Composition

Litmus contains between 10 to 15 different dyes, with 7-hydroxyphenoxazone being the most important.

Properties

Litmus is a black powder, soluble in water, which changes color in acidic environment to red and blue in basic solution.

Availability

Litmus powder and litmus paper can be purchased from chemical suppliers and online. It can be found on eBay and Amazon.

Isolation

Litmus can be isolated from certain lichens, though you'll need an appreciable amount of them to extract useful quantities of litmus.

Projects

  • pH indicator

Handling

Safety

Litmus has low toxicity and no special protection or safety measures are required when handling it. However, it can stain, so wear disposable gear.

Storage

In closed bottles.

Disposal

No special disposal is required. Discard it as you wish.

References

Relevant Sciencemadness threads