Essay on Gilbert Newton Lewis, Alessandro Volta, Luigi Galvani

A. Gilbert Newton Lewis

Gilbert Newton Lewis was born on October 25, 1875 in West Newton Massachusetts.  He learned to read at a young age of three.  At the age of 16 years old, he attended the University of Nebraska but transferred to Harvard University where he received his B.S. After briefly working as a teacher, he returned to Harvard and finished his M.A. in 1898 and PhD in 1899.  In 1907, he became an assistant professor at the Massachusetts Institute of Technology (MIT). When he left MIT he was appointed as the Chairman of the Department of Chemistry and the Dean of the College of Chemistry at UC Berkeley in 1921.  He held the position for thirty four (34) years until his sudden demise on March 23, 1946.  He had always believed that a chemistry department should simultaneously teach science and advance it focusing always on the fundamental principles rather than its technical applications.  (George B. Kaufman 2) He was most remembered for his accomplishments in University of California Berkeley which he helped transformed its chemistry department into a world-class center for research and teaching. (George B. Kaufman 2)

One of Lewis’ contributions is his Theory of Acids and Bases.  According to Lewis, acids-bases reactions should not be limited to a mere transfer of hydrogen ions or protons.  Prior to Lewis, other chemists have propounded that acids-bases reaction as simply a transfer of hydrogen ions.  This is the case with Svante Arrhenius who defined an acid as a substance that releases hydrogen ions in solution and a base as a substance that forms hydroxyl ions.  On the other hand, both Lowry and Bronsted stated that an acid is a substance from which a proton can be obtained while a base is a substance that can remove a proton from an acid.  In simple terms, for Arrhenius and Lowry and Bronsted the acid-base reaction was limited to the transfer of proton. 

The approach of Lewis was quite different while not necessarily inconsistent with the position of Arrhenius, Lowry and Bronsted.  He thought that there are acid-base reactions which are not necessarily proton based.  For him, not all acid-base reactions involve protons or connected with water.  He proposed that an acid-base reaction involves the transfer of electrons.  For him, an acid is an electron-pair donor while a base is an-electron pair acceptor.

In effect, Lewis’ acid-base theory is an extension of Arrhenius Lowry and Bronsted.  The following arguments can therefore be suggested: All Arrhenius acids are also Lowry-Bronsted’s acids and Lewis’ acids. (Lewis Theory 1) All Lowry-Bronsted’ acids are also Lewis acids. (Lewis Theory 1) But not all Lewis acids are either Arrhenius or Lowry-Bronstead’s acids. (Lewis Theory 1)

B. Alessandro Volta

Alessandro Volta, the person who is best known for discovering current electricity, was born on February 18, 1745 in Como, Italy.  Resisting pressure from his parents to enter priesthood, Volta immersed himself in the study of the sciences, particularly electricity.  He became a professor of Physics at the Royal School in Como. Volta was deeply interested in the study of electricity early in his career which led him to publish his first book on static electricity at the age of twenty-four.  It was in the year 1774 where Volta invented the electrophorus, his first important contribution to the science of electricity.  The electrophorus was a device which provided a source of electric potential utilizing the principle of electrostatic induction.  The advantage of this device is that it allowed for a more sustained and easily replenish-able source of static electricity. 

However, even with Volta’s discovery of electrophorus, there was still no other device

that is capable of producing a steady and continuous flow of electricity.  While the electrophorus was an improvement from the other devices, it can only produce short bursts of static electricity.  Luigi Galvani helped solve this riddle.  In 1786, Galvani discovered that the muscles in a frog’s amputated legs would contract every time an electrical machine was discharged near the leg. (“Alessandro Volta” 2)  He proceeded to investigate about this and discovered further that if here merely attached a copper hook to the nerve ending and then pressed the hook against an iron plate on which the leg was resting the legs will contract even in the absence of an electrical machine.  He then referred to this electricity as animal electricity.

Volta however was unconvinced that the animal was the source of the electricity but instead considered it as a mere passive source of electricity. (Alessandro Volta 3)  The main source of electricity, for him, was the metal which he called the metallic or contact electricity.  He proceeded to conclude that when two dissimilar metals were placed in contract with each other using a certain type of fluid, it would produce an electrical effect.  According to him, an electrical circuit will be formed when two dissimilar metals were held in contact and joined by a moist third body.  Such was the basis for the eventual construction of an electric battery as the first source of current electricity.  The energy or force generated was called voltage in honor of Alessandro Volta

Luigi Galvani

Luigi Galvani born on September 9, 1737 at Bologna was a famous Italian anatomist and physiologist.  He briefly studied theology and then shifted to medicine at the University of Bologna.  Upon graduating, he was appointed lecturer of anatomy and surgery at Bologna until he began experimenting on electrophysiology. 

One of his important discoveries was what he eventually called as the animal electricity.  He noticed the twitching in the muscles of the legs of the frogs when its legs were placed on top of an iron railing and connected by copper hooks.  He noted similar reactions when the muscles where laid out on a metal during a thunderstorm.  Based on this, he came to the conclusion that the source of the electricity was the tissues of the frog itself.  The conclusion was however found out to be false by Volta who discovered that the animal tissue was not the source of electricity but a mere passive conductor and that it was the metal that is the source of electricity. (Luigi Galvani 1)

Another one of his important discovery was the Galvanic Cell which is also sometimes called the Voltaic Cell.  The Galvanic Cell is a device that is capable of converting chemical energy of oxidants and reductants into electrical energy.  This is conducted by physically separating an oxidizing agent and a reducting agent and connecting them with a wire that will allow electrons to flow.  The device which allows the electrons to flow is called the electrodes which are composed of the electrode and the anode. 

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Essay on Walther Hermann Nernst, Josiah Willard Gibbs & Svante Arrhenius

Walther Hermann Nernst

Walther Hermann Nernst was a German Physicist who was well-known for his immense contribution in electrochemistry, thermodynamics, and photochemistry.  Born in Briesen, Prussia in 1864, he became a pioneer in the field of chemical thermodynamics.  One of his contributions is the third law of thermodynamics for which he was awarded the Nobel Prize in Chemistry in 1920. (Joachim Schummer 2) He spent his early years studying physical and mathematics in the Universities of Zurich, Berlin and Graz. He received his Ph.D. summa cum laude in 1887 for his doctoral thesis which was about the effects of magnetism and heat on electrical conductivity.   In 1905, he was first appointed as professor of physical chemistry in Berlin.  In 1924, he became a professor of physics at Berlin.  It was his close association with Wilhelm Ostwald and other physical chemists that Nernst began his important researches in the field of electrochemistry.

Nernst has always been interested with electrochemical studies.  He was particularly interested with the dependence on concentration of galvanic cells such as batteries.  He started by investigating the diffusion of electrolytes in one solution and compared the diffusion between two solutions with different electrolyte concentration. 

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One of the most important contributions of Nernst was made when he was in his twenties.  He devised a mathematical expression showing that electromotive force is closely dependent upon temperature and concentration in a galvanic or electricity-producing cell.  This was subsequently known as the Nernst Equation.  The equation below shows what the Nernst Equation is:

E_cell = E⁰_cell - (RT/nF)lnQ

            The Nernst Equation may also be restated in the following manner

E_cell = E⁰_cell - (2.303*RT/nF)logQ

or

at 298K, E_cell = E⁰_cell - (0.0591 V/n)log Q

Based on the Nernst equation, the following are its values: E_cell = cell potential under nonstandard conditions (V); E⁰_cell = cell potential under standard conditions; R = gas constant; T = temperature; n = number of moles of electrons exchanged in the electrochemical reaction; F = Faraday's constant; and Q = reaction quotient. 

According to Walther Nernst, the Nernst equation is a useful equation as it allows the cell voltages to be predicted in a given reaction.  It may also be used to find the concentration of one of the components of the cell. (Anne Marie Helmenstine 2) For instance, in case when a zinc electrode is submerged in a solution which is connected by a salt bridge to another solution containing a silver electrode.  The Nernst equation can be helpful in determining the initial voltage of the cell given the particular solution.  In this example, suppose that the first acidic solution is at 0.80 M Zn²⁺ solution while the second solution is at 1.30 M Ag⁺ solution.  The cell potential can be determined which is at 1.57 V. (Anne Marie Helmenstein 2)

Josiah Willard Gibbs

Josiah Willard Gibbs was a famous American mathematical engineer who earned the distinction as one of the greatest mathematical physicist since Isaac Newton.  He was also one of the few American physicists to gain recognition internationally for his contribution and achievement. (“Josiah Willard Gibbs2)

Born on February 11, 1830 in New Haven, Connecticut, J. Willard Gibbs was known for devising the theoretical foundation for chemical thermodynamics as well as physical chemistry.  He started his education at the local Hopkins Grammar School where he was described by his classmates as friendly but withdrawn which is an indication that he was involved very little in social life.  Yale University and subsequently earned the Ph.D. in engineering in the same university in 1863 which was the first doctorate of engineering to be conferred in the United States. He initially taught Latin and natural philosophy until he left for New Haven to study in Europe where he attended lectures by scientists from Paris, Berlin and Heidelberg.  He was later on appointed as professor of mathematical physics at Yale in 1871.

In simple terms, the Gibbs free energy states that energy that is unevenly distributed in a closed system will continue to move and be passed around until such time that there is no longer any further energy exchange possible. (“Science: Unknown Equilibrist” 2)  This is what Gibbs called the thermodynamic equilibrium.  How thermodynamic equilibrium is attained is explained using the Nernst Equation.  The Gibbs Free Energy equation is one of the most important discovered of Josiah Willard Gibbs.  Its equation is shown below:

G, is defined by G = H − TS,

In this equation, G is the energy that is being absorbed in a reversible process at constant pressure and constant temperature.  H stands for the enthalpy while S stands for entropy.  The changes in the values of G correspond to changes in free energy.  It also presupposes that the process happens at a constant temperature and pressure. 

Gibbs free energy is important because it determines when there will be a reaction depending on the changes in the values of G. It states the conditions when a chemical reaction will occur.  For instance, when the ΔG is positive, it only means that the energy is in the equilibrium position.  For this reason, there will be no chemical reaction unless energy is supplied or added so that the equilibrium will be changed.  On the other hand, when the ΔG is negative there is a spontaneous chemical reaction which will proceed to equilibrium.

Svante Arrhenius

Svante Arrhenius is considered as one of the founders of physical chemistry or the field of science in which physical laws are used to explain chemical phenomena.  He was born on February 19, 1859 in Sweden.  His intelligence became manifest at a young age of three where he taught himself how to read which was surprisingly against the wishes of his parents.  He also acquired an excellent mathematical skill just by observing his father perform accounting work.  His interests as a young boy were mathematics and physics.  He entered the University of Uppsala studying mathematics, chemistry and physics.  He eventually left Uppsala in 1881 to work on the conductivities of electrolytes at Stockholm under the famous physicist E. Edlund. His association with Edlund led to the preparation of a thesis entitled Investigations on the galvanic conductivity of electrolytes where he concluded that electrolytes when dissolved in water become split or dissociated into electrically opposite and negative ions.  He also concluded that the degree of dissociation depended on many factors such as the nature of the substance and the concentration of its solution. (“Svante Arrhenius: Biography” 2004)  Surprisingly, his ideas were not accepted by the faculty.  As a result, he barely passed his dissertation. 

The Arrhenius Equation is shown below:

k=A*exp^(-E_a^/R*T)

In this equation, T refers to the temperature which is measured in Kelvin.  R refers to the gas constant which is measured in R. E_A refers to the activation energy.  The Arrhenius Equation simply states that when the temperature remains constant, chemical reaction will not be any faster or slower.  However, when the temperature becomes higher, chemical reaction will also happen faster.  This is because the molecule particles start to collide at a faster rate.  As the molecules react to the change in temperature and as they move faster, the greater will be the number of collisions that can lead to a reaction.  In simple words, the higher the collision rate the higher the resulting kinetic energy which leads to a chemical reaction. 

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