Carnegie Mellon University

Product Tampering: Procedure

To measure the pH of a solution, tear a strip of litmus paper about 1 1/2 inches long from the dispenser or, if using precut strips, remove one from the container.  Put a few drops of the test solution into one side of the testing tray.  Dip the tip of the litmus paper into the solution, then compare its new color with the chart on the dispenser to determine the pH. Remember to wear your safety glasses at all times.


  1. Measure the pH of the vinegar marked "Produced Before Possible Tampering"
  2. Measure the pH of the vinegar marked "Produced After Possible Tampering"

How do the two vinegar samples compare? Has there been tampering?  If so, is there too much acid, or not enough?  Should the police be informed?

See the product tampering data sheet [.pdf].


Rinse out testing tray with water, then dry it.  Return sample bottles, testing tray, and litmus paper dispenser to the teacher. Discard the used litmus paper.