By Oxana Fox
Updated Mar 24, 2022

In chemistry, the logarithmic pH scale determines whether a solution is acidic, neutral, or basic. The standard scale ranges from 0 to 14, with 7 indicating neutral pH (pure water). Solutions with a pH below 7 are acidic, while those above 7 are basic. Litmus paper is a simple yet reliable indicator that changes color in response to pH: blue litmus turns red in acidic environments.

Safety First

Always treat unknown liquids as hazardous. Before handling any sample, put on rubber gloves and safety goggles to protect your skin and eyes.

Materials Needed

• Rubber gloves
• Safety goggles
• Blue litmus paper
• Scissors

Step‑by‑Step Procedure

1. Wear your gloves and goggles.
2. Using scissors, cut a one‑inch strip of blue litmus paper.
3. Dip the paper into the liquid for just a moment and withdraw it immediately.
4. Observe the portion of paper that contacted the liquid. If it turns red, the solution is acidic; if it remains blue, the solution is either neutral or basic.

Limitations

Blue litmus paper only indicates the presence of an acid—it does not provide the exact pH value. For a precise measurement, use pH indicator strips that include a color‑coded scale on the packaging.

TL;DR

Blue litmus paper signals acidity but not the exact pH. For detailed pH readings, use indicator strips with a reference chart.

Warning

Always handle unknown substances with caution. Protective gear is essential when working with potential acids, bases, or other chemicals.