A German chemist who was known as one of the founders of the field of physical chemistry. He won the Nobel Prize in Chemistry in 1909 for discovering that chemical reactions occur at finite rates, and that these rates can be used to figure out the strengths of acids and bases.
He obtained both his undergraduate degree and his Ph.D. from the University of Tartu, Estonia.
He became a member of the International Committee on Atomic Weights in 1906 and served on the committee until World War I erupted.
He had five children with his wife Helene von Reyher, who he married in 1854.
He won the Nobel Prize in Chemistry the year after Ernest Rutherford did.