Who he was
Svante Arrhenius grew up in Uppsala, Sweden, and studied physics and chemistry at Uppsala University. For his doctorate he measured how well solutions of salts conduct electricity, and he noticed something odd: the more dilute the solution, the better each unit of dissolved salt conducted. His explanation was so new that his examiners gave the thesis a low grade.
Key contributions
Ions in solution. In 1887 Arrhenius proposed that salts, acids and bases split into ions as soon as they dissolve in water, whether or not a current flows. At the time many chemists found this absurd: how could sodium and chlorine exist separately in water? The idea explained the conductivity of solutions and why dissolved salts lower the freezing point about twice as much as sugar does, and it became the foundation of solution chemistry.
Acids and bases. From the ionic theory came the first modern definitions: an acid produces hydrogen ions in water and a base produces hydroxide ions. Neutralization is then simply
Activation energy. In 1889 he explained why a small rise in temperature can make a reaction much faster. Only molecules with enough energy, more than a threshold he called the activation energy, react. His equation, , is still used in every kinetics course.
Key idea
Arrhenius taught chemists to think of solutions as mixtures of ions and of reactions as needing an energy barrier to be crossed. Both ideas run through the lessons on acids and bases and on reaction rates.
Carbon dioxide and climate. In 1896 he made one of the first calculations of how the Earth’s temperature depends on the amount of carbon dioxide in the air, a pioneering study of the greenhouse effect.
Prizes and legacy
He received the 1903 Nobel Prize in Chemistry, the first Swede to win a Nobel Prize. As director of the Nobel Institute for Physical Chemistry from 1905, and a member of the Nobel Committee for Physics, he played a large part in the early years of the Nobel Prizes. The Arrhenius definition of acids and bases and the Arrhenius equation keep his name in every chemistry textbook.
Connections to your lessons
His work underpins the lessons on acids and bases (the Arrhenius definition), activation energy (the Arrhenius equation) and colligative properties (why ionic solutes have a larger effect).
Timeline
- 1859Born at Vik, near Uppsala; the family moves to Uppsala, where he grows up and goes to school.
- 1884Presents his doctoral thesis on the electrical conductivity of solutions at Uppsala. It is given a low grade: his teachers doubt the idea behind it.
- 1886With support from Wilhelm Ostwald, travels to work in leading laboratories in Germany and elsewhere in Europe.
- 1887Publishes the theory of electrolytic dissociation: in water, salts, acids and bases split into ions, even without an electric current.
- 1889Explains why reaction rates rise steeply with temperature, introducing the idea of an activation energy (the Arrhenius equation).
- 1895Becomes professor of physics at Stockholm University (then Stockholms Högskola).
- 1896Calculates how changes in atmospheric carbon dioxide would change the temperature of the Earth, an early study of the greenhouse effect.
- 1903Awarded the Nobel Prize in Chemistry, the first Swede to receive a Nobel Prize.
- 1905Becomes director of the new Nobel Institute for Physical Chemistry in Stockholm, a post he holds until shortly before his death.
- 1927Dies in Stockholm.
Sources and further reading
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