The pH scale is the measurement of the H1 concentration (hydrogen ions) in a solution. It is used to measure the acidity or alkalinity of a solution. The pH scale ranges from 0 to 14. A neutral solution has a pH of 7, one with a pH greater than 7 is basic, or alkaline; and one with a pH less than 7 is acidic. The lower the pH below 7, the more acidic the solution. Each whole-number drop in pH represents a tenfold increase in acidity.
| pH Value |
Examples of Solutions |
| 0 |
Hydrochloric acid (HCl), battery acid |
| 1 |
Stomach acid (1.0–3.0) |
| 2 |
Lemon juice (2.3) |
| 3 |
Vinegar, wine, soft drinks, beer, orange juice, some acid rain |
| 4 |
Tomatoes, grapes, banana (4.6) |
| 5 |
Black coffee, most shaving lotions, bread, normal rainwater |
| 6 |
Urine (5–7), milk (6.6), saliva (6.2–7.4) |
| 7 |
Pure water, blood (7.3–7.5) |
| 8 |
Egg white (8.0), seawater (7.8–8.3) |
| 9 |
Baking soda, phosphate detergents, Clorox™, Tums™ |
| 10 |
Soap solutions, milk of magnesia |
| 11 |
Household ammonia (10.5–11.9), nonphosphate detergents |
| 12 |
Washing soda (sodium carbonate) |
| 13 |
Hair remover, oven cleaner |
| 14 |
Sodium hydroxide (NaOH) |
