The pH of most aspirin tablets ranges from 2.8 to 3.2. The pH is measured by dissolving the aspirin in water, and the level varies depending on the concentration of aspirin, or salicylic acid, in the water. The pH can range from 2.4 to 6 in laboratory conditions.
The pH scale ranges from 0 to 14. Zero is acid, 14 is alkaline, and 7 is neutral. The pH measures the number of hydrogen ions an acid or base forms when dissolved in water. If the solution results in a higher concentration of positively charged hydrogen ions, the substance is an acid. If the solution results in a higher concentration of negatively charged hydroxide ions, it is a base or alkaline.