S.P.L. Sørensen: Key Facts About Inventor of the pH Scale Celebrated in Google Doodle

The pH scale that is widely accepted and used by scientists didn’t actually exist until 1909. Before then scientists had to rely on using adjectives to describe the acidity or basicity of a substance they were working with.

That scale was created by S. P. L. Sørensen, a Danish chemist who was working in Copenhagen at the time of his creation. The chemist was honored with an interactive Google Doodle Tuesday. The doodle shows Sørensen surrounded by his pH scale and allows users to guess the pH of certain items like a tomato, soap and a lemon.

What is the pH scale?

The pH scale is used to classify the level of acidity a basicity of a substance. The scale is numbered from zero through to 14, and on modern scales each number has a corresponding color on a spectrum. Today we have pH strips, pieces of paper that react with a substance’s acidity or basicity and change color when they come in contact with one of them. The color the strip turns to after it comes in contact with the substance corresponds to a spot on the pH color spectrum.

Water is usually neutral, right in the middle of the scale, assigned the number seven. On a pH strip, water is white. To the right of neutral are the numbers eight through 14 that represent a pH of a basic substance, with 14 representing the most basic. Water from the ocean, ammonia and lye all have spots along the scale of basic substances. To the left of where water is on the scale are more acidic substances, such as vinegar and lemon juice.

Six facts about S. P. L. Sørensen:

S. P. L. Sørensen's full name was Sørensen Peter Lauritz Sørensen.

In 1901 he took on the role of the director of the chemical department at the Carlsberg Laboratory, the lab of the beer company Carlsberg.

His wife, Margrethe Høyrup Sørensen, helped him with his research into the thermodynamics of protein chemistry during his time as director.

The pH scale is a means to measure the hydrogen ion concentration in a solution or liquid. Before it existed there was no way to do so.

Sørensen’s creation allowed brewers at the Carlsberg lab to follow the fermentation process in beer production to make sure it was on track.

He originally planned to study medicine, but changed career paths when he was in school.

ph test A worker checks the pH level of desalinated water in the laboratory at the desalination plant in Palma de Mallorca on April 4, 2014. The pH scale was initially invented in 1909 by chemist S.P.L. Sorensen. Jaime Reina/Getty Images