The higher the pH reading, the more alkaline and oxygen rich the fluid is. The lower the pH reading, the more acidic and oxygen deprived the fluid is. The pH range is from 0 to 14, with 7.0 being neutral. Anything above 7.0 is alkaline, anything below 7.0 is considered acidic.
Acids corrode active metals. Even gold, the least active metal, is attacked by an acid, a mixture of acids called 'aqua regia,' or 'royal liquid.' When an acid reacts with a metal, it produces a compound with the cation of the metal and the anion of the acid and hydrogen gas. .
Bases release a hydroxide ion into water solution. (Or, in the Lowry- Brønsted model, cause a hydroxide ion to be released into water solution by accepting a hydrogen ion in water.).
The pH scale measures how acidic or basic a substance is. It ranges from 0 to 14. A pH of 7 is neutral. A pH less than 7 is acidic, and a pH greater than 7 is basic. Each whole pH value below 7 is ten times more acidic than the next higher value. For example, a pH of 4 is ten times more acidic than a pH of 5 and 100 times (10 times 10) more acidic than a pH of 6. The same holds true for pH values above 7, each of which is ten times more alkaline (another way to say basic) than the next lower whole value. .
Pure water has a pH of 7.
Ammonia has a pH of 11.0- 12.
An apple has a pH of 2.9 - 3.3.
A carton of milk has a pH of 6.4 - 7.6.
Lemonade has a pH of 2.2 - 3.
Normal rain has a pH of about 5.6. It is slightly acidic because naturally present carbon dioxide from the Earth's atmosphere dissolves in the rain drops to form carbonic acid.
Rain measuring between 0 and 5 on the pH scale is acid rain.
Human blood stays in a very narrow pH range around (7.35 - 7.45). Below or above this range means symptoms and disease. If blood pH moves to much below 6.8 or above 7.8, cells stop functioning and the patient begins to die. The ideal pH balance for a healthy body is slightly more alkaline than acid measuring 7.