THE BEECHMONT CREST GUIDE TO BIOLOGICAL TERMS
pH SCALE
The pH scale measures the concentration of hydrogen ions (H+) in a solution. Cells typically require a neutral pH of 7 to perform their life-sustaining functions. (Pure water has a neutral pH of 7.) A solution with a higher pH or a lower pH can kill cells.
- If a solution has a pH that is less than 7, it is acidic.
- An acidic solution has a large number of hydrogen (H+) ions.
- In a solution, an acid releases H+ ions.
- If a solution has a pH greater than 7, it is basic.
- A base is a molecule that takes H+ ions from a solution.
pH values of some common substances:
gastric acid: 1
saliva: 6
pure water: 7
oven cleaner: 13