Jacobus Henricus van’t Hoff – First Nobel Prize Winner (1901)

Jacobus Henricus van’t Hoff – First Nobel Prize Winner (1901)

Jacobus Henricus van’t Hoff

Biography & Contributions

Jacobus Henricus van't Hoff was a Dutch physical-chemical, organic chemist and Nobel laureate born on August 30, 1852 – died on March 01, 1911. Van’t Hoff was the first Nobel Prize in the field of chemistry. His best-known works are on chemical kinetics, chemical equilibrium, osmotic pressure, and stereochemistry. He also proposed van’t Hoff factor.

In 1874, he accounted for the phenomenon of optical activity by assuming that the chemical bonds between carbon atoms and their neighbors were directed towards the corners of a regular tetrahedron.

He also introduced the modern concept of chemical affinity. In 1886, he showed a similarity between the behavior of dilute solutions and gases.

Van’t Hoff worked on Svante Arrhenius's theory of the dissociation of electrolytes and in 1889 provided physical justification for the Arrhenius equation.

Pasteur had discovered that when isomers are crystallized, they differ optically. One compound rotates a beam of polarized light to the left, and the other rotates it to the right. He believed the structures of the compounds were asymmetrical but Van't Hoff theorized that the optical isomers differed in their molecular arrangement. He stated that the four chemical bonds of carbon atoms, represented as four directions lying in the same plane, actually are directed to the corners of a tetrahedron. Such three-dimensional carbon atoms can exist in only two forms, which are mirror images of each other, and the opposite tetrahedral arrangements explain the oppositional optical rotation.

Van't Hoff also studied double- and triple-linked carbon atoms. He also proposed that the effects of circularly polarized light in the atmosphere cause optically inactive substances to become optically active.

In experiments that attempted to explain certain oxidation processes, he discovered the law of mobile equilibrium, which showed that the internal temperature equilibrium of a system shifts to oppose the external temperature around it.

Van't Hoff conducted experiments on the effect of a salt solution on pure water and determined values by methods such as altering vapor pressure and temperature. In 1886, he demonstrated that solute particles in a dilute solution behave much the same as particles of a gas and occupy a volume equal to the solvent.

Van’t Hoff Factor

Van’t Hoff factor is a measure of the effect of a solute upon colligative properties such as osmotic pressure, relative lowering in vapor pressure, elevation of boiling point and freezing point depression. The van't Hoff factor is the ratio between the actual concentration of particles produced when the substance is dissolved and the concentration of a substance as calculated from its mass.

Osmotic Pressure Phenomenon 

Osmotic Pressure is defined as the measure of the tendency of a solution to take in water by osmosis. Osmotic Pressure is of vital importance in biology as the cell's membrane is selective toward many of the solutes found in living organisms.

Osmotic Pressure phenomenon of osmotic pressure arises from the propensity of a pure solvent to move through a semi-permeable membrane and into a solution containing a solute to which the membrane is impermeable.

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