Litmus

Definition

Litmus is a water-soluble mixture of different dyes extracted from lichens, primarily used as a pH indicator. It changes color in response to acidic or basic conditions; red in acid and blue in base.

5 Must Know Facts For Your Next Test

1. Litmus is commonly used in paper strips or solutions to test the acidity or basicity of substances.
2. It turns red under acidic conditions (pH < 7) and blue under basic conditions (pH > 7).
3. Neutral litmus paper is purple, indicating a neutral pH of around 7.
4. Lichens are the natural source for extracting litmus dye.
5. Litmus tests are quick and easy, making them useful for preliminary identification of pH levels.

Review Questions

• What color does litmus paper turn when exposed to an acidic solution?
• From what type of organism is litmus extracted?
• In what form can litmus be used to test pH levels?

Related terms

pH:

A scale used to specify the acidity or basicity of an aqueous solution.

Acid: A substance that increases the concentration of hydrogen ions (H+) in a solution.

Base: A substance that reduces the concentration of hydrogen ions (H+) in a solution.