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About Alkalinity

Alkalinity is the measure of the capacity of bases to neutralize acids. In other words, it is the measure of how much acid can be added to a particular liquid without causing significant changes in the liquid's pH level. Furthermore, alkalinity is not the same as the pH because the solution does not have to have a high pH (be strongly basic) to have a high level of alkalinity, according to WQA.

  1. The Facts

    • Alkalinity is essentially a measure of the water's capacity to buffer. It does not refer to the actual pH level but instead to the water's ability to resist changes in its pH, according to Boulder. Water that has a low level of alkalinity is easily susceptible to changes in its pH, while water with a high level of alkalinity can easily resist those changes.

    Features

    • Certain compounds are added to water in order to neutralize acidity. These compounds are basic solutions that are sometimes referred to as buffering materials, according to Boulder. The most popular bases used for this purpose are carbonate and bicarbonate; however, ammonium, sulfides, hydroxide, borates, silicates, organic ligands, and phosphates are also used.

    Function

    • As the amount of acid is added to a body of water, the pH of the water decreases, according to Boulder. The decreasing level of the water's pH consumes the water's buffering capacity. A pH level of below 5.5 has a very weak ability to buffer and will drop quickly if more acid is added to the water. If the solution has a pH level of less than 4.5, it no longer has any alkalinity.

    Example

    • Alkaline products are useful in removing fatty, oily and acidic stains and therefore have a lot of use in the detergent industry. Soap and other soap based products are alkaline, according to WQA, because soap is a medium alkaline salt. Other cleaning and detergent products can be made with any level of alkalinity depending on their specific needs. Furthermore, while hard surface cleaners and automatic dishwasher detergents are alkaline, most hand washing detergents are neutral. Hand washing detergents are effective while neutral because they are activated by the actual motion of rubbing.

    Effects

    • The measure of alkalinity is found through titration. The titrant (a known acid) is added to a specific volume of treated water. The particular volume of the acid that is required to bring the sample of water to a specific pH level is the alkalinity of the sample. Besides regulating the pH of a solution, alkalinity can also regulate its metal content, according to Boulder. Carbonate and bicarbonate ions in water are able to remove toxic metals (in particular, arsenic, cadmium, and lead) by precipitating these metals from the solution.

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