2. Life
Johannes Nicolaus Brønsted
1879 Born in Varde, Denmark
A great physical
chemist was born!
1899 Received degree Chemical engineering
1906 Published first
paper
Electron affinity
1908
Inorganic and physical
Received Ph. D and
chemistry University of
became professor Copenhagen
1923 Introduced
protonic theory
Acid based reactions and
electronic theory
1947 Was elected to
Danish parliament
Didn’t accept due to
illness
2
1947 Passed away
3. Brønsted Catalysis Equation
Johannes Nicolaus Brønsted
log k = α × log (Ka) + C
k= reaction rate Ka= acid dissociation
constant constant
The speed of the chemical
reaction with relation to temperature. The quantitative strength of an acid in
solution.
α= gradient 3
C= intercept
4. Brønsted-Lowry Theory
Johannes Nicolaus Brønsted
• Developed independently by Brønsted and Lowry (at
University of Cambridge) in 1923
• Explains reaction between an acid and a base
". . . acids and
bases are
P P P P P P substances that
are capable of
P P + P P P P P P splitting off or
+ B taking up
A B A hydrogen ions,
respectively."
A is an acid B is a base A is a base B is an acid
Acid is capable P P P
having a proton P P P P
removed
(proton donor)
Base is capable of
removing/taking a proton
P (proton acceptor) 4
P = Proton
B ‘steals’ proton from A
5. Example of Brønsted-Lowry Theory
Johannes Nicolaus Brønsted
① HI and H2O react
• HI + H2O H3O+ + I¯ NOTE: H2O is amphoteric,
② Now H3O+ is the acid and I¯ is the base so it behaves as a base
in this reaction.
• H3O+ + I¯ HI + H2O
③ Once again HI and H2O are produced
④ Process continues
HI + H 2 O H 3 O + + I¯
Acid
Proton donor Conjugate base
Base Conjugate acid 5
Proton acceptor
Johannes Nicolaus Brønsted by Aditya Krishnan, Bailey McKittrick and Paula Zinser.
JohannesNicolaus Brønsted was born in a town in Denmark called Varde in 1879. He received his degree in chemical engineering at the age of 20. He published his first paper on electron affinity seven years later. He received a Ph. D in inorganic and physical chemistry and went on to become a professor both at the University of Copenhagen. In 1923, he introduced the protonic theory on acid based reactions and electronic theory. He took part in politics and was elected to the Danish parliament in 1947, but didn’t accept due to his deteriorating health. He passed away the same year at the age of 68.
Brønsted developed this equation to determine the relationship between the strength of an acid and its catalytic activity. It is on a logarithmic scale, where: k is the speed of the chemical reaction when it occurs at a certain temperature (k is constant), Ka is the quantitative measure of the strength of the acid in a solution. When plotted on a graph, it gives a straight line with but with slope α, and intercept C.
Brønsted and a scientist from Cambridge called Lowry came up with this theory independently within months of each other, and so both are credited with its discovery. The theory explains the reaction between an acid and a base. Brønsted and Lowry theorized that an acid is capable of having a proton removed (so it is called a proton donor), and a base is capable of removing and taking a proton (so it is called a proton acceptor). So, during a reaction between an acid and a base, the base will ‘steal’ a proton from the acid; this will turn the previously basic solution to an acid solution, and the previously acidic solution will become basic. Brønsted described this as ". . . acids and bases are substances that are capable of splitting off or taking up hydrogen ions, respectively”, meaning that an acid-base reaction is the transfer of a proton from the acid to the base.Remember, the proton mentioned is actually a H+ ion: a H+ ion has no electrons and no neutrons, just one proton, which the acids and bases fight for!
TheBrønsted-Lowry Theory explains acid-base reactions. Here is an example. Hydrogen iodide (acidic) reacts with water (amphoteric, behaving as a base), forming hydronium (acidic) and an iodine ion (basic). Since the iodine is basic and the hydronium is acidic, the iodine once again takes the proton from the hydronium, forming hydrogen iodide and water once again. This process continues. So hydrogen iodide is the acidic proton donor, water is the basic proton acceptor, and this forms a conjugate acid hydronium and conjugate base, an iodine ion.
These are all the sources used for this presentation, including information and images/clipart. All sources (science journals, websites and books) are cited in MLA format.
