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Johannes Nicolaus Brønsted
b. February 22, 1879, Varde, Denmark
d. December 17, 1947, Copenhagen, Denmark

Johannes Nicolaus Brønsted was Danish physical chemist known for a widely applicable acid-base concept identical to that of Thomas Martin Lowry of England. Though both men introduced their definitions simultaneously (1923), they did so independently of each other. Brønsted was also an authority on the catalytic properties and strengths of acids and bases. His chief interest was thermodynamic studies, but he also did important work with electrolyte solutions.

Brønsted's childhood, youth and education

Johannes Nicolaus, c. 1890
The son of a civil engineer, Johannes Nicolaus was born on February 22nd, 1879 in Varde, a small town in West Jutland. His mother died soon after his birth, and his father remarried. However, Johannes was only 14 years old when his father also died. These tragic family circumstances must have left Johannes and his elder sister Ellen in a very traumatic situation.


In a picture from the garden of Hesselvig Enggard (taken around 1890) Johannes has already (symbolically) started to show independence by keeping a certain distance to the rest of the group in the picture. His two years older sister Ellen on the far left in the picture shared the fate of early death of her parents. She died, like her mother, in childbirth in 1919 at the age of 42.


The farm Hesselvig Enggard, c. 1890
by Skjern River near Herning in Jutland
Johannes' father Sophus Theodor Brønsted was a civil engineer working for 'Hedeselskabet', a corporation founded to reclaim moorland by draining, irrigation, and planting. In this farm (which is now a fish farm) the family was right in the middle of a part of Jutland which - a hundred years ago - was a deserted area, covered with heather. But for a boy this was Paradise. Johannes may have aquired his never fading interest for nature here at this spot by the river.


Newly graduated students from 
'Metropolitanskolen' in 1897. 
Brřnsted is #2 from right in the middle row
After the loss of both parents the young Brønsted and his sister moved to Copenhagen with their stepmother and Brønsted attended the 'Metropolitanskolen' for three years . He passed his 'studentereksamen' (University entrance examination) in the summer of 1897. The picture shows Brønsted and his class mates. The most well-known of these is probably Niels Bjerrum right in the middle of the picture. Later Bjerrum became Brønsteds colleague and competitor in physical chemistry and he remained his lifelong friend.


Family gathering at the village of Espergarde, North Zealand, Denmark, summer 1897. J.N. Brønsted with his white 'studenterhue' (undergraduates cap) and his sister Ellen Brønsted (third from the left) together with Pauline Bülow, their father's sister (far left) and other members of the Bülow family.


In the autumn of 1897 Brønsted took up studies at the (old) Polytecnic Institute in the street Solvgade in Copenhagen. He completed his first degree studies in engineering in 1899, and began studies in pure science at Copenhagen University. He took his 'magister' degree in Chemistry in 1902. The painting shows Brønsted in those years (about 1900). It was painted by his sister Ellen who had graduated as a sculpturer and painter from the Art College for Women under the Academy of Fine Arts.


From the days of study at the chemical laboratories at the Polytechnic Institute. Brřnsted is in both pictures. It is quite likely that the instructor (in white lab. coat) is Professor Emil Petersen


Mr. and Mrs. Brønsted in 1903.
The dog (Sam) was the first of many to follow

Brønsted with a dog at Erikshab 1903
At the Polytecnic Institute Brønsted met Charlotte Louise Warberg, who in 1902 became one of the very first female engineers in Denmark. They were married in 1903 and moved into a flat at Forchhammersvej in Copenhagen. Contrary to Brønsted, Charlotte Louise was from a large family from Erikshab in Fyn; a sister was married to the Danish artist Johannes Larsen of Kerteminde. A painting by him is seen on the wall. Brønsteds interest in dogs and cigars are obvious from this picture and from the one below taken on a visit to Erikshab.


The newly appointed,
young Professor of
Chemistry, 1910 
There was no academic position immediately available for Brønsted in 1902 and it took three years before he could return to the University Chemical Laboratories to take up a position as an assistant. However, it is interesting to note that in the meantime Brønsted initiated his studies of the thermodynamic quantity 'affinity'. Thus, his pioneering thermodynamic studies of the interconversion of sulfur modifications (as praised by Nernst) was published already in 1904, and it looks as if his former teacher Professor Emil Petersen has played a major role here. In all Brønsteds publications from that time Emil Petersen is acknowledged for his generous support and for letting Brønsted do experimental work in his laboratory. Unfortunately that collaboration didn't last long. Petersen died at the age of 51 in 1907. In 1905 Brønsted started to work at his 'affinity' measurements on binary mixtures (sulfuric acid and water). He presented his doctoral thesis on that subject in 1908 and luckily a new chair of chemistry was instituted at the University that same year. It came to an academic battle between two candidates: J.N. Brønsted and Niels Bjerrum. Bjerrum had defended his doctoral degree a few months after Brønsted had defended his. After a difficult time for the judges, the choice finally fell on Brønsted, and on December 24th it was announced in the morning newspapers that Dr. Phil. Johannes Nicolaus Brønsted was the new Professor (with consensus). His employment was valid from 17 December 1908 , which should later prove to be exactly 39 years before his death.

A long adventurous and strange career had started. Naturally it would involve a great deal of scientific activities, but Brønsted had "a wealth of interests outside his science" (From 'The Brønsted Memorial Lecture' delivered before The Chemical Society in London on Feb. 3rd, 1949)

Brønsted at work

The Physicochemical Institute at
Blegdamsvej 19 in Copenhagen

Brønsted in the lab
(after 1930)


Brønsted at his desk

The Acid Base Theory of Brønsted and Lowry

In 1923, within several months of each other, Johannes Nicolaus Brønsted (Denmark) and Thomas Martin Lowry (England) published essentially the same theory about how acids and bases behave. Since they came to their conclusions independently of each other, both names have been used for the theory name.

In 1923, Johannes Nicolaus Brønsted introduced a new view of acids and bases. An acid was defined as a compound tending to give up a proton (or hydrogen ion), while a base was one tending to combine with a proton. This new view accounted for all the facts already satisfactorily accounted for by the old view of Svante Arrhenius. In addition it represented a greater flexibility that made it possible to extend acid-base notions into areas in which the old view was inadequate.

Brønsted - Lowery Theory:
Acid - proton donor.
In an equation, a Brønsted - Lowery acid must have hydrogen in its formula.
Base - proton acceptor.

A Brønsted - Lowery base is hard to generalize for all equations. It may be a negative ion. You may have to look at the products. Find one that contains hydrogen. If the negative part of this product was in a reactant that did not contain hydrogen, that reactant is most likely the base. This theory focuses on the action of protons in reactions. Since protons are in the nucleus of an atom, the hydrogen ion is the only source of protons in a normal chemical reaction. The definition of acids and bases is broadened because no specific ions must be formed, but hydrogen is needed in the reaction to produce the proton.

Two important terms are used in association with this theory:

Conjugate base - the particle that remains after an acid gives up a proton.

Conjugate acid - the particle formed when a base accepts a proton.

An acid-base reaction involves the transfer of a proton from an acid to a base:

Hydronium ion - formed by a hydrogen ion and a water molecule - H3O+. Since a hydrogen ion is nothing more than a proton (a bare positive charge), when formed, this proton is immediately attracted to a polar water molecule forming a hydronium ion. For this reason, hydrogen ions never actually exist in water solution. Autoionization of water includes the hydrogen ion transfer from one water molecule to another one:

You could benefit from reading additional explanations on:
The Acid Base Theory of Brønsted and Lowry
as well as from the reading the original text of a Brønsted's paper
J. N. Brønsted, Some Remarks on the Concept of Acids and Bases,
Recueil des Travaux Chimiques des Pays-Bas (1923) Volume 42, Pages 718-728

Pictures from Brønsted's travels

Brønsted and Bjerrum entering the harbor in Harwich, England on 14 June, 1923 at 6 p.m. on the 'Dronning Maud'. 


Bjerrum and Brønsted with two other danish chemists (? and C.J.H. Madsen) in front of one of the Cambridge colleges, attending the annual IUPAC meeting 17-20 June 1923.


Brønsted at the Whirlpool Rapids above the Niagara Falls in September 1912. He had started out from Copenhagen on 22 August with Profs. E. Biilmann and Julius Petersen (and a few other chemists) to cross the Atlantic by the ship Oscar II. They were attending a conference in Washington D.C., where they were introduced to President Taft at a garden party in the White House. On this trip Brønsted also visits scientific colleagues in Rochester, Boston (T.W. Richards, Harvard) and Ithaca (Bancroft, Cornell).


Brønsted "on Debye's balcony"
20 February, 1927
Brønsted spent 8 months in the U.S. from August, 1926 until April, 1927., visiting V.K. LaMer at Columbia University, N.Y. and as a visiting professor at Yale University. It was during this stay that Brønsted established arrangements for a later donation of 100.000 USD from the Rockefeller Foundation to build his (badly needed) new Physicochemical Institute at Blegdamsvej 19 in Copenhagen.
Brønsted in the trip
to the U.S., 1926-27

Brønsted as a host

Needless to say Brønsted had a lot of scientific visitors over the year from 1920; Victor K. LaMer was the first from outside Denmark. Others were: G. Hevesy, C.V. King, E.A. Guggenheim, W.F. K. Wynne-Jones, Mary and Martin Kilpatrick and R. P. Bell, and the Danish chemists A. Tovborg-Jensen and J. Koefoed.

R.P. Bell (1907-96) at the new 'Brønsted Institute' on the street Blegdamsvej 19 in Copenhagen. Ronnie Bell spent four years with Brønsted during 1928-1932. He became Brønsted's most famous pupil. He published only one paper with Brønsted, but four on his own; all taking advantage of experimental methods originated by Brønsted. However, it is typical for Bell's publications that they all had a component of (modern) theoretical considerations.

It is interesting to know that during his Copenhagen period he must have started thinking about writing his quite remarkable series of theoretical papers (in the 1930's) concerning chemical rate theory and quantum mechanical tunnelling, before he initiated his main field of interest - acid-base catalysis and isotope effect studies - with enormous effort and with a constant stream of papers over several decades.

But Bell was young in Copenhagen and had other things to learn, including fluent Danish, which he mastered for the rest of his life. Before he married Margery around 1930, and then came to live in one of the flats on top of the new Brønsted Institute at Blegdamsvej, he came to know a number of artists in Copenhagen, e.g. the Danish author Tom Kristensen. Bell loved his novel "Harvark" (Havoc), which he had read many time in Danish. He also came to know the Danish actor Robert Storm Petersen. Bell loved Storm-P's intriguing drawings with their sense of humour and strange philosophy. R. P. Bell became a member of the Danish Royal Society and he received an honorary degree from the Technical University of Denmark in 1969. Many young Danish chemists made advanced studies in Bell's laboratories in Oxford and (later) Stirling, and benefited from his warm feelings for Denmark, all dating back to his "Copenhagen Days" with Brønsted.

Visitors from the United States. Harned (far right) with Scatchard; then follows Mrs. Brønsted, Mrs. Harned and J. N. Brønsted. The picture is taken at the City Hall in Copenhagen.
(From left to right) Front Row: George von Hevesy, Agnes Petersen, Fritz Haber. Back Row: Niels Bohr, Einar Gontelberg, Johannes N. Brønsted. The picture was taken outside the Copenhagen Polytechnic Institute, June 18, 1920.

With family and friends

J.N. Brønsted (1910) together with three sisters. From left: Louise Brønsted, Christine Mackie and Alhed Larsen (married to Johannes Larsen, the artist).


J.N. Brønsted (far right) and Louise Brønsted (center) with friends archaeologist H.C. Broholm (with glasses) and Mrs. Broholm (second from left). On the back of the photo is written: "Montgomery and his staff before the battle, July 30, 1944".


Brønsted cleaning the shoes of grandson Jesper after a field trip to the forest of Tisvilde Hegn, Northern Zealand 1939. "On that particular trip", tells Jesper, "he showed me in his Ziess 8x30 binoculars a group of long-tailed titmice (Aegithalos candatus) and demonstrated the somewhat cruel hunting habits of the ant-lion (Myrmeleon formicarius). On another field trip, on bicycle, to Saltbak Vig and Asnas, Zealand, in 1943, he taught me the voice of the avocet (Recurvirostra avocetta) and explained the significance of the shape of the bill of variour Wading birds. Both of my grandparents were active birders. There was about one meter of books on birds on their bookshelves."

Brønsted as an artist

Presumeably inspired by his artist sister Ellen and /or by Johannes Larsen in Kerteminde Brønsted tested his talents for painting and drawing in the period 1915 - 23.

Painting by Brønsted from about 1916. His wife Louise and their son Peter Oluf. The chess board is still in the family's possession.


The "Spanish Cherry Tree". Painting by Brønsted from the home in Birkerod, North Zealand, where Brønsted lived with his family from 1908-1923. This house was taken over by his older daughter who still owns the house. Louise Brønsted moved back here after Brønsted's death.


Painting by Brønsted. This painting was submitted to the Artist's Spring Exhibition in 1923, but was not accepted for exhibition.


Mr. and Mrs. Brønsted delivering a musical performance in their first home. Brønsted himself played the piano and is said to have had a nice barytone voice.

His firm opposition to Nazism during World War II won him election to the Danish Parliament (1947), but illness prevented him from taking his seat.

The Second World War served only to strengthen the ties which bound him to English things and English people, and he never had any doubts as to the rightness or the eventual outcome of the struggle. From the first day of the German occupation he spent several hours daily listening to the broadcast news from London, and he also read widely in English history and biography: In 1945 he still had on his table a list of English Foreign Secretaries from 1769 onwards. The occupation also turned his attention to public affairs in general, in particular the wexed question of Schleswig and the Danish-German frontier, about which he spoke and wrote in his usual forthright manner. Nevertheless, it was a surprise to many of his friends when in 1947 he accepted nomination as a candidate for the Danish parliament, and a still greater one when on October 28th he was elected. He took the responsibility seriously, and immediately began to study parliamentary procedure, but he was overtaken by his last fatal illness before he could take his seat, and died on December 17th. (From Bell's Memorial Lecture, 1949)


Birkerod Kirkegard February 22, 1979. At the 100 years anniversary of the birth of Brønsted Prof. J. Kofoed lay down a wreath on his grave. At right Brønsted's daughter Alhed.

This text has been compiled from the biographies of Brønsted available in the Internet: (1, 2).

(updated & corrected on August 2, 2003)