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Nancy K. Brown Skin Dictionary letter P section
| pH: |
pH is defined as the negative logarithm of hydrogen activity. It is a measure of the acidity or alkalinity of a solution. The pH value states the relative quantity of hydrogen ions (H+) contained in a solution. The greater the concentration of H+, the more acidic the solution and the lower the pH. In pure water (H2O) the H+ activity can be considered the same as the H+ concentration. pH measures the degree of acidity or alkalinity relative to the ionization of water. Pure water at 25 degrees Celcius has a pH of 7, which is neutral. The pH scale ranges from 0 to 14. Solutions with a higher [H+] than water (pH less than 7)are acidic; solutions with a lower [H+] than water (pH greater than 7) are basic or alkaline. A solution with a pH less than 0 is considered a super acid. |
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