The negative log of the hydrogen ion concentration in a solution is called the "pH."
The pH of a solution is the negative log of its hydrogen ion concentration. It is a measure of acidity or alkalinity that is very useful in chemistry. It can be measured using chemical indicators or with a device called a pH meter.
History
In 1934, Glen Joseph, a chemist working at a laboratory run by the California Fruit Growers Exchange, asked his friend Arnold Beckman at the California Institute of Technology for help finding a better way to measure the acidity of lemon juice. Fruit growers used the acidity of fruit to determine its ripeness and quality. The device Beckman built worked so well that Joseph asked him for another. Beckman subsequently founded a business manufacturing and selling pH meters to laboratories nationwide.
Significance
Before the pH meter, the citrus industry had difficulty measuring the acidity of lemon juice because the sulfur dioxide they used as a preservative bleached litmus paper. The use of pH meters, which were more accurate, eliminated the need for sulfur dioxide.
Function
While the pH meter was originally invented to measure the acidity of lemon juice, it quickly found a wide variety of applications in chemistry. The pH factor is important in many chemical reactions and experiments; in acid-base titration, for example, chemists determine the concentration of an acid or base in a solution by monitoring pH as another chemical is added. As of 2010, pH meters remain invaluable for innumerable uses in chemistry.
Tags: acidity lemon, acidity lemon juice, lemon juice, measure acidity, hydrogen concentration, measure acidity lemon, negative hydrogen