

Dr Søren Sørensen (1868-1939) developed the pH scale during his pioneering research into proteins, amino acids and enzymes - the basis of today’s protein chemistry.  Basically meaning ‘the power of hydrogen’, the scale provides a simple and universal measurement of the amount of hydrogen ions in a solution, which affects its acidity and how it reacts chemically. 


What’s the number?

The concentration of hydrogen ions is determined by measuring the current generated in an electrochemical cell when the ions migrate to oppositely charged electrodes. Sørensen used a negative logarithm of the hydrogen concentration to create a scale from 0-14, where a pH of less than 7 is an acid, 7 is neutral and higher than 7 is an alkali.  So water has a pH of 7, lemon juice 2.4 and bleach 12.5.  The pH of beer is 4.5.

The applications of the pH scale have been countless, ranging from foodstuffs and cosmetics to chemicals and pharmaceuticals. Just about every liquid has had its pH measured at some time to determine how it will react and interact with living organisms.