Litmus and pH paper contain a chemical that changes color as it makes contact with an acid or base. The paper will turn red in acids and blue in bases. Usually a color chart is provided with the pH paper in order for the user to determine the pH range of the indicator. Using paper to determine the pH is not as accurate as a pH meter, which provides results with the exact pH measurement; whereas the pH paper only results in a pH range.
Measuring with pH paper
Find the pH of a substance using pH paper. Dip the end of the pH strip into the chemical or substance you want to test. After a couple of seconds, remove the paper and compare the color of the pH strip to the color chart provided with the pH paper kit. Do not re-use a pH paper to retest or test another chemical. Always use a new pH strip.
Test pH Paper on Saliva
Test the litmus or pH paper using your saliva to test the color changes of the pH paper. Take two pieces of the pH paper (one pink and one blue). Place the paper in your mouth and remove after a few seconds. Determine whether your saliva is acidic or basic. If the paper changed from red to blue, this indicates that the saliva is basic. If the paper changes from blue to red, this indicates that the saliva is acidic. If nothing happened, the saliva is neutral.
A pH indicator is a chemical compound that is added to a solution in order to determine the pH of the solution more easily. Basically, the pH indicator can detect hydrogen ions and causes the color of the solution to change depending on the pH level. Litmus paper contains a pH indicator that turns the paper either red or blue depending on the pH level. Try comparing different indicators, such as methyl orange or crystal violet with the pH paper to see the accuracy of the litmus paper.
Compare Colors of pH paper
Compare the colors on the pH paper to the color scale on the pH paper package in order to determine the pH of the sample. Use different solutions, such as water, milk, soda, orange juice, to test the pH paper and practice determining colors on the color scale. Using different solutions can help visualize the different colors on the scale and determine the exact pH range.
About the Author
Based in Huntington Beach, Calif., Dana Schafer has been writing environmental articles and grant proposals since 2006. Schafer has written for Grace Unlimited Corporation and Youth Have Vision. Schafer is in the process of receiving a Master of Science in biology from California State University, Long Beach.