What is pH?
Acidic and basic are two extremes that describe chemicals, just like hot and cold are two extremes that describe temperature. Mixing acids and bases can cancel out their extreme effects; much like mixing hot and cold water can even out the water temperature. A substance that is neither acidic nor basic is neutral. 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. For example, a pH of 10 is ten times more alkaline than a pH of 9. Pure water is neutral, with a pH of 7.0. When chemicals are mixed with water, the mixture can become either a
pH Problems What do bluish-green stains on a home’s fixtures mean? “pH” problems? What is “pH”? “pH,” written with a lower case “p” and a capital “H,” is the negative logarithm of the effective hydrogen-ion concentration. In simple terms, pH refers to whether the water is acidic or alkaline. The pH scale goes from 0 to 14, with a pH of 7 generally considered neutral. Water with a pH below 7 is considered acid, and water with a pH above 7 is considered alkaline. Most natural waters fall in the range of 5 to 8. Certain areas lacking limestone are notorious for having low pH (acidic water). If you see bluish-green stains on the tub or sinks of a home using copper water pipes, acidic water is corroding the metal parts of the plumbing system. If a home has brass water faucets or copper tubing whose solder contains lead, high levels of lead may be found when water stands in the pipes overnight. Running the water before drinking generally eliminates this problem. Typically, waters with a low
pH is the measurement of the hydrogen ion concentration, [H+]. This value ranges from 0 to 14 pH. Values below 7 pH exhibit acidic properties. Values above 7 pH exhibit basic (also known as caustic or alkaline) properties. Since 7 pH is the center of the measurement scale, it is neither acidic nor basic and is, therefore, called “neutral.” On way to measure pH is by indicators, materials that are specifically designed to change color when exposed to different pH values. The color of a wetted sample paper is matched to a color on a color chart to infer a pH value. pH paper is available for narrow pH ranges (for example, 3.0 to 5.5 pH, 4.5 to 7.5 pH and 6.0 to 8.0 pH), and fairly wide pH ranges of 1.0 to 11.0 pH.
