Arrhenius Equation

Svante August Arrhenius (1859-1927) was a Swedish chemist and physicist who received a Nobel prize in chemistry (1903) for his theory of electrolytic dissociation.  He hypothesized that once an electrolyte is dissolved into a solvent it would dissociate into oppositely charged ions. Before he even came up with this hypothesis, other chemists believed that electrolytes dissolved as uncharged molecules that could only be separated by strong electric forces.  This hypothesis made by Svante Arrhenius explained a wide range of phenomena and laws beyond electrochemistry. 

Arrhenius is mostly known for his equation that describes the effect of temperature on the rate of a reaction:

where Ea and A are called the arrhenius paramaters and
k = raction rate constant
A = pre-exponential factor
Ea = activation energy
R = gas constant
T = temperature in Kelvin

Arrhenius suggested that the most important step in a chemical reaction was the formation of activated molecules from the reactant molecules and that both states were in equilibrium, separated from each other by the activation energy.  He explained how the temperature is dependent of the reaction rate due to a change in equilibrium.  As the temperature is increased the molecules that are more activated are set to undergo reaction.

Avogadro's Law

Lorenzo Romano Amedeo Carlo Avogadro di Quaregna e di Cerreto (1776-1856), also known as Amedeo Avogadro, was an Italian chemist who is most famous for his contribution with the molecular theory, which is now known as Avogadro's Law.

Amedeo was born in Turin, Italy into a family of well established lawyers.  He also followed into the footsteps of his family and got a bachelor of jurisprudence in 1792.  In 1796, just four year later, Amedeo received his doctorate of ecclesiastical law and soon began his practice.  However, after approximately 5 years Amedeo began to take an interest in mathematics and physics (back then it was known as philosophy).  In 1809 he started teaching at a high school and this is where he declared his hypothesis of Avogadro's Law.  It wasn't until 1858 that Avogadro's Law was accepted, when another chemist named Stanislao Cannizzaro was able to explain the organic exceptions of the law.

Avogadro's Law states that at a constant temperature and pressure, equal volumes of gases contain equal amounts of molecules.  If the amount of gas in a container is increased then the volume is increased.  According to this law,  V1/n1 = constant and after a change in the volume and mole number then V2/n2 = constant.  By combining these two equations we then get V1/n1 = V2/n2 which can be derived from the kinetic theory of gases under the assumption of an ideal gas.

Amedeo Avogadro believed that particles could be composed of molecules and that molecules could be composed of atoms.  The number of molecules in a mole was defined to be Avogadro's number.  Avogadro's number has been determined experimentally to be 6.0221415 x E-23 molecules per gram mole.