How to Use Litmus Paper Accurately

Litmus paper is frequently used to teach basic chemistry.

Litmus paper is commercially available laboratory paper used to test the pH of a liquid. The pH of a liquid is a measure of whether it is alkaline or acidic and to what extent. The litmus paper contains several types of dyes that react to acids and alkalinity. Traditionally, litmus paper turns red when acidic, blue when alkaline and purple when neutral. Most modern litmus paper has a color range to indicate precisely the pH of a solution. For example, the paper may display dark red for a very acidic solution and light red for a slightly acidic solution.

Things You'll Need

• Beaker
• Long tweezers

Instructions

1. Pour the solution in an open beaker for easy access.

2. Pick up a strip of litmus paper with long tweezers. Pinch the litmus strip gently so as to not break the delicate paper.

3. Dip half of the length of the litmus paper strip into the solution and immediately place the litmus strip onto a paper towel to dry.

4. Examine the litmus paper's color to determine whether the solution is acidic, alkaline or neutral. All litmus paper strips include a color guide indicating what each color means.

Tips & Warnings

• Do not leave the litmus paper dipped in the solution for more than a few seconds, as the paper may become damaged. Another term for alkaline is known as "basic."

References

• "Chemistry: The Central Science"; Theodore E. Brown, H. Eugene LeMay, Bruce E. Bursten and Catherine Murphy; 2008
• "Practical Chemistry Labs: A Resource Manual"; Leonard Saland; 1989