What is a sample's buffering capacity as it relates to alkalinity?

Document ID

Document ID TE117

Published Date

Published Date 03/31/2021
What is a sample's buffering capacity as it relates to alkalinity?
Relationship between sample buffering capacity and alkalinity
Alkalinity is a measure of the capacity of water or any solution to neutralize or “buffer” acids. This measure of acid-neutralizing capacity is important in figuring out how “buffered” the water is against sudden changes in pH.

The most important compounds in water that determine alkalinity include the carbonate (CO32-) and bicarbonate (HCO3-) ions. Carbonate ions are able to react with and neutralize 2 hydrogen ions (H+) and the bicarbonate ions are able to neutralize H+ or hydroxide ions (OH-) present in water. The ability to resist changes in pH by neutralizing acids or bases is called buffering.

Alkalinity should not be confused with pH which is a measure of the hydrogen ion (H+) concentration; the pH scale shows the intensity of the acidic or basic character of a solution at a given temperature. The reason alkalinity is sometimes confused with pH is because the term alkaline is used to describe pH conditions greater than 7 (basic).

For more information on what is being measured with alkalinity, please reference What ion is being measured when testing for alkalinity?

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