The formula for pH, which is pH = -log[H₃O⁺], is derived from the work of multiple scientists, and it isn't attributed to one single person. However, the concept of pH and the logarithmic scale was heavily influenced by the work of Søren Peder Lauritz Sørensen. While he did not introduce the mathematical formula, it is a direct result of his work.
Understanding pH
The pH scale is used to measure the acidity or basicity of a solution. Here’s a breakdown:
- pH Scale: Ranges from 0 to 14, with 7 being neutral.
- Acidic: Solutions with a pH less than 7 are acidic.
- Basic (Alkaline): Solutions with a pH greater than 7 are basic.
- H₃O⁺: Refers to the hydronium ion concentration in a solution.
The Formula's Origin
Although the mathematical expression for pH is not typically linked to a single person, its foundation is attributed to:
- Søren Peder Lauritz Sørensen: Introduced the pH scale while working at the Carlsberg Laboratory in 1909. He defined pH as a way to measure the concentration of hydrogen ions. Although he didn't give the formula, the concept and scale he provided are foundational to it.
- Subsequent Scientific Development: The formula pH = -log[H₃O⁺], came later, when scientists and chemists recognized the relationship between the negative logarithm of the hydronium ion concentration and the pH scale that Sørensen proposed.
Applying the Formula
- The formula pH = -log[H₃O⁺] states that the pH is the negative logarithm (base 10) of the hydronium ion concentration.
- This formula lets us mathematically express the acidity or alkalinity of a solution.
- It makes working with hydrogen ion concentrations much more practical, given their vast range in nature.
Practical Examples
- A solution with a hydronium ion concentration of 1.0 x 10⁻⁷ M has a pH of 7 (neutral).
- A solution with a hydronium ion concentration of 1.0 x 10⁻³ M has a pH of 3 (acidic).
- A solution with a hydronium ion concentration of 1.0 x 10⁻¹⁰ M has a pH of 10 (basic).
The equation pH = -log[H₃O⁺] is now universally used to quantitatively express the acidity of a solution using the pH scale which was first introduced by Sørensen. While Sørensen didn't create the formula itself, his work laid the groundwork for its development and widespread use.
