Acidity is the quantitative capacity of a water sample to neutralize a base to a predetermined pH value. Greater acidity indicates higher concentration of acids present and more potentially corrosive the water. Acidity is caused by a variety of acids including mineral acids, organic acids, and even carbon dioxide in the form of carbonic acid. Today, our water supplies are becoming more contaminated with corrosive chemicals from industrial dumping and ever-growing amounts of carbon dioxide in the atmosphere. Acidity measurements are an essential means to define and control pollution in sewers, lakes, and rivers. Monitoring acidity in soils and fish farming helps to maintain an adequate growing environment. Acidity also affects the quality of food and beverages, such as wine, fruit juices, sauces, and olive oil.
The concept of pH and acidity are easily misunderstood. All aqueous solutions can have the pH measured but that is not the same as an acidity measurement. To determine the acidity of a solution it necessary to titrate the solution with a base, such as sodium hydroxide, to a pH endpoint. The most common pH endpoint is phenolphthalein, when the indicator is added to a solution the solution will change to a pink color at pH 8.2. Solutions of different acidities (regular orange juice versus low acid) can have the same pH value but require different amounts of base to reach the pH 8.2 end point.
The pH meter was invented to determine the acidity of orange and lemon juice. The meter was used in place of the indicator due interferences that caused the color change to not be seen. Many customers continue to use a pH meter and graduated burette to perform this simple titration.
Technology has advanced with automatic titration systems that have unique algorithms to dose the base precisely in order to determine either a pH endpoint or an equivalence point. Hanna offers a wide range of products from basic chemical test kits to advanced automatic titration systems.