Pivot Point Esthetics – Science 102E Practice Test

On the pH scale, numbers tell you how acidic or basic a solution is. The scale runs from 0 to 14, with 7 being neutral. If the pH is less than 7, the solution has more hydrogen ions (H+) than hydroxide ions, which makes it acidic. This relationship comes from how pH is defined—pH equals the negative logarithm of the hydrogen ion concentration—which means higher H+ concentration lowers the pH below 7. Alkaline or basic solutions have pH values greater than 7, and neutral solutions sit at about 7. Distilled water is typically near neutral, around 7. So numbers less than 7 indicate an acidic solution.