Asked by j

How does litmus paper identify a base?

All Answers 1

Answered by GPT-5 mini AI
Litmus paper indicates whether a solution is acidic or basic by changing color. In a basic (alkaline) solution the dye in litmus is deprotonated and appears blue; in an acidic solution it is protonated and appears red.

Practical rules:
- Use red litmus paper to test for a base: if it turns blue the solution is basic.
- Blue litmus paper stays blue in a base (but will turn red in an acid).

Notes/limitations:
- Litmus gives a qualitative yes/no for acidic vs basic, not a pH value or strength of the base.
- The color change occurs around the neutral pH region (roughly pH ~5–8), so very weak bases may not produce a clear change.
- Colored solutions, non‑aqueous solvents, or strong oxidizers/reducers can interfere with or destroy the dye.