S. P. L. Sørensen


Søren Peter Lauritz Sørensen was a Danish chemist, famous for the introduction of the concept of pH, a scale for measuring acidity and alkalinity.

Personal life

S. P. L. Sørensen was born in Havrebjerg, Denmark in 1868. The son of a farmer, he began his studies at the University of Copenhagen at the age of 18. He wanted to make a career in medicine, but under the influence of chemist S. M. Jørgensen decided to change to chemistry.
While studying for his doctorate he worked as assistant in chemistry at the laboratory of the Danish Polytechnic Institute, assisted in a geological survey of Denmark, and also worked as a consultant for the Royal Naval Dockyard.
He was married twice. His second wife was Margrethe Høyrup Sørensen, who collaborated with him in his studies.

Work

From 1901 to 1938, Sørensen was head of the prestigious Carlsberg Laboratory, Copenhagen. While working at the Carlsberg Laboratory he studied the effect of ion concentration on proteins, and because the concentration of hydrogen ions was particularly important, he introduced the pH-scale as a simple way of expressing it in 1909. The article in which he introduced the scale described two methods for measuring acidity which Sørensen and his students had refined. The first method was based on electrodes, whereas the second involved comparing the colours of samples and a preselected set of indicators.