Antoine Lavoisier's Understanding of Caloric and the Properties of Water

The process of science is a wonderful thing, which is what drives me into trying to understand the history of science.  My recent dive into this is reading Antoine Lavoisier's Elements of Chemistry, as it is one of modern chemistry's first textbook written by one of it's fathers. Now this isn't the easiest piece of literature to read, not because of the language, it excels in that category, but the font chosen makes the s's appear as f's. Difficulties aside, here is a quote I fell in love with, showing his understanding of the cohesion of water molecules before there was an understanding of hydrogen bonds, and heat before there was an understanding of molecular kinetic energy.

It is, perhaps, more natural to suppose, that the particles of caloric have a stronger mutual attraction than those of any other substance and that these latter particles are forced asunder in consequence of this superior attraction between the particles of the caloric, which forces them between the particles of other bodies, that they may be able to reunite with each other.  We have somewhat analogous to this idea in the phenomena which occur when a dry sponge is dipt into water: The sponge swells; its particles separate from each other; and all its intervals are filled up by the water.  It is evident, that the sponge, in the act of swelling, has acquired a greater capacity for containing water than it had when dry.  But we cannot certainly maintain, that the introduction of water between the particles of the sponge has endowed them with a repulsive power, which tends to separate them from each other; on the contrary, the whole phenomena are produced by means of attractive powers; and there are, first, The gravity of the water, and the power which it exerts on every side, in common with all other fluids; 2dly, The force of attraction which takes place between the particles of the water, causing them to unite together; 3dly, The mutual attractions of the particles of the sponge with each other; and, lastly, The reciprocal attraction which exists between the particles of the sponge and those of the water.  It is easy to understand, that the explanation of this fact depends on properly appreciating the intensity of, and connection between, these several powers.  It is probable, that the separation of the particles of bodies, occasioned by caloric, depends in a similar manner upon a certain combination of different attractive powers, which, in conformity with the attractive powers, which, in conformity with the imperfection of our knowledge, we endeavour to express by saying, that caloric communicates a power of repulsion to the particles of bodies.

Just as a background fact, Caloric was Lavoisier's term for kinetic energy, and at that time was considered to be a fluid or gas that would flow through matter, making it either hot or cold.  Just as heat flows from hot to cold, Caloric would flow from a hotter material to a cooler one until it reaches an equilibrium.  All of these observations, now obvious to us, were new and exciting for the scientists at the time, and to think there was a fluid that flows dictating temperature wasn't far off from the truth considering that matter with more kinetic energy expands according to PV = nRT.

I recommend this read to anyone interested in the history of our chemical body of knowledge, or to show respect to the people who worked undyingly hard to make these pivotal discoveries.

References:
Lavoisier, Antoine Laurent. Elements of Chemistry, in a New Systematic Order, Containing All the Modern Discoveries. New York: Dover Publications, 1965. Print.

When the Catholic Church and Science Get Along

I asked myself yesterday, while watching TV, what is used to make the papal smoke turn either white or black, and how do they make sure there is no false alarm.  In my research I found that they previously used wet straw to make the black smoke and nothing added to make the white smoke. But in an article by The Guardian, I found that they now use an electronic smoke machine, starting in 2005, where potassium perchlorate (KClO₄), anthracene (3 fused benzene rings), and sulphur is used to make the black smoke, while potassium chlorate (KClO₃), lactose and a pine resin is used to make the white smoke.

So how does this work?

Black
The anthracene (from tar) helps the burnt carbon from the paper flow upwards in the smoke instead of remaining in the ash.  The KClO₄ is used to aide the combustion of the paper to create the chunks of carbon. What carries all of this upward is the water that is generated in the chemical reaction of combustion. Just think of it as the burnt carbon as being graphite, which produces a back colour.

White
What creates the white smoke is the existence of unburnt paper, or other unburnt fuel, rising up with the heat.  The paper is thermally broken apart in a process called pyrolisis, leaving small white particles of unburnt cellulose, or from the added resin, rising up as the combustion product of H₂O rises out of the chimney. Just think of the particles of unburnt fuel being like table sugar, which gives off a white colour.

References:
Via: The Guardian

Egyptian Blue: Calcium Copper Silicate

In a recent article by Scientific American, a story is told of Calcium Copper Silicate (Egyptian Blue) being the first artificial pigment made by humans, and soon to be utilized, once again, as a nano ink for biomedical imaging.  I'm not going to go over the details of the article, but I will present some background information of this soft blue colour.

Being the first recorded synthetic pigment, you may ask how it was originally synthesized.  The first procedures, in 3000 B.C., involves the heating of sand, calcium carbonate, copper, and an alkali substance to obtain this blue pigment having a composition of CaCuSi₄O₁₀.  The reaction below is a general understanding of the reaction, where the molecules can be variable in a number of different ways.

Cu₂CO₃(OH)₂ + 8SiO₂ + 2CaCO₃ → 2CaCuSi₄O₁₀ + 3CO₂ + H₂O

The blue colour comes from the absorption of the copper, which can range from the blue, seen above, to a much darker blue, depending on how pure the mixture is. But what wasn't known at that time, was that when irradiated with visible light, the compound emits IR photons, which is the property that will conduct the imaging technologies.

References:
Via: Scientific American
Wikipedia

Friedel-Crafts Alkylation

The Friedel-Crafts Alkylation reaction is used to add an alkyl group to an aromatic ring in the presence of a strong lewis acid.  This reaction was developed by Charles Fiedel (France) and James Crafts (USA) in 1876, in studying reactions involving the creation of carbon-carbon bonds, some of the most valuable technology in organic chemistry.

This reaction involves taking an aromatic ring and adding an alkyl halide (Cl-R1) with a strong lewis acid (AlCl₃), where the alkyl halide can exist as a tri-substituted, all the way to a methyl.  The chemistry of this reaction involves the AlCl₃ to strip the Cl from the alkyl halide, forming a carbocation (R⁺), followed with the π electrons of the aromatic ring to grab the carbocation. The AlCl₄^- can now strip the H away from the position where the R added on the aromatic ring, reverting the catalyst back to it's original form, and the final product to be formed.

2/23/2013 - Soap

  To start off, the formal definition of a soap is a water-insoluble fatty acid mixed with an organic base or an alkali metal, which produces a carboxylic acid salt, and in-turn increasing the solubility in water.  Although they technically are chemically modified, they are usually not considered synthetic.  Soaps have been dated back to at least 2300 years, possibly originating from the Celts, and their original procedure for creating these soaps was to boil animal fat in water with some form of ash, usually from wood.  This saponifies the fat to the free fatty acids.  The chemical in the ash that is actively turning this fat into soap is potassium carbonate (K₂CO₃), which first deprotonates the fatty acid producing a bi-product of HCO₃, while the potassium acts as a counter ion, producing the salt.

  This carboxylic acid salt can interact with water now since it's head is more charged, rather than an uncharged fatty acid.  The way this soap now works is that the long carbon chain interacts with oil (from skin, hair or any other source on your body), while the charged end interacts with water allowing the oils to be washed away with an excess of water.

References:
Myers, D. Surfactant Science and Technology, 3rd ed. Wiley-Interscience: New Jersey, 2006.

7/22/2012: Bleach

Now everyone is familiar or should be familiar (for those who don't clean) with bleach. Bleach is a chemical known for its cleaning capabilities and its ability to remove pigments or colour from objects, and its disinfectant ability.  Bleaching is a general form and consists of a couple different methods, but in particular I will be talking about the use of Sodium hypochlorite (NaOCl) being that it is the most popular.  The power of this chemical comes from it's oxidizing ability when it combines with water to make HClO, since it is a molecule of high electronegativity.  The oxidation process goes as follows 2HClO_(aq) + 2H⁺ + 2e^- → Cl_2(g) + 2H₂O . There has also been very extensive research in it's disinfectant process.  The first synthesis performed by Claude Louis Berthollet in 1789 is very simple where it consists of passing chlorine gas through sodium hydroxide: 

Cl_2(g) + 2NaOH _(aq)  → NaCl _(aq) + H₂O _(l)

07/12/2012 - Organolithium Ether Cleavage

There comes a point in a compound's life when there is a question of whether there is an easier way to make it, and in 1930 Karl Ziegler questioned this with organolithium compounds.  Not only did he find more simpler ways of preparing such organolithium compounds but he developed many applications for the use of the light metal.  The largest application of these compounds is in organic chemistry as organolithium reagents, used in creating those precious carbon-carbon bonds. But one of the first applications that Ziegler developed was the ability of Lithium to cleave an ether bond, demonstrated in the following reaction:

PhCH₂OMe + 2Li → PhCH₂Li + MeOLi

7/11/2012 - Generation of Alkyl Radicals

The next year in 1929 one of the pioneers of radio chemistry, Friedrich Adolf Paneth, an Austrian scientist who did the majority of his early work at Königsberg University, completed a journey set out by Sir Edward Frankland.  This discovery gained humanity the ability to create alkyl radicals, and the identification of such radicals through their ability to displace a metallic mirror (silver mirror etc.).  This was performed through the pyrolysis (thermal decomposition) of a lead organometallic with the general formula of PbR_4.

7/10/2012 - Beginnings of Carbonyl Chemistry

In 1928 a chemist by the name of Walter Heiber, also known as the father of carbonyl chemistry, started a systematic study of many metal carbonyls.  This allowed him to discover many of the hidden catalytic properties of these utilizable compounds.  Two of his most famous reactions were in the realm of Iron chemistry with the two following reactions:

Fe(CO)₅ + H₂NCH₂CH₂NH₂ →  (H₂NCH₂CH₂NH₂)Fe(CO)₃ + 2CO
Fe(CO)₅ + X₂ → Fe(CO)₄X₂ + CO

7/9/2012 - Synthesis of Tetraethyllead Pt. II

In the year of 1922 two chemists working with General Motors Corportation Thomas Midgley and T.A. Boyd discovered an additive to gasoline that would prevent engine knocking, meaning uncontrollable combustion.  This additive was Tetraethyllead, an organometallic discovered back in Germany in 1854 but not utilized until this point.  This great discovery 'lead' to the creation of new gasoline solutions which have since phased out due to the high toxicity of lead in the exhaust fumes.  The synthesis of Pb(C₂H₅)₄ is performed through the following reaction of a sodium lead alloy with chloroethane:

4NaPb + 4CH₃CH₂Cl → (CH₃CH₂)₄Pb + 4NaCl + 3Pb

Source: 

7/8/2012 - Synthesis of Polyphenylchromium Compounds

The past couple of days I have been recovering from my dentist reaching into my mouth and stealing my precious wisdom teeth, and dealing with my new found tolerance to most pain killers making it much more difficult than it should be.  But I have finally got my hands back on my organometallics text book so that I can continue in my history of organometallic chemistry.  I last left off in 1917 with the synthesis of Lithium alkyls, which then brings our journey to 1919 with a German chemist named Franz Hein.  This man's claim to fame came to him with the synthesis of polyphenylchromium compounds, being the first sandwich compounds to be made.  This synthesis was performed by the mixture of CrCl₃ (Chromium (III) Chloride) with PhMgBr (Phenylmagnesium bromide) to create a series of these phenylchromium salts that were later found to be made of biphenyl, not phenyl, and oriented in a way making them look like a sandwich.

What are Particles?

As I continued to read the biography on Paul Dirac, The Strangest Man by Graham Farmelo, I came across this very ensightful quote of Dirac's which gives a very good sense on how we can imagine particles.

When you ask what are electrons and protons I ought to answer that this question is not a profitable one to ask and does not really have a meaning.  The important thing about electrons and protons is not what they are but how they behave - how they move.  I can describe the situation by comparing it to the game of chess.  In chess, we have various chessmen, kings, knights, pawns and so on.  If you ask what a chessman is, the answer would be [that]  it is a piece of wood, or a piece of ivory, or perhaps just a sign written on paper, [or anything whatever].  It does not matter.  Each chessman has a charateristic way of moving and this is all that matters about it.  The whole game of chess follows from this way of moving the various chessmen.

Source: Farmelo, Graham. The Strangest Man. Basic books, Philidelphia, 2009. 

4/29/2012 - Synthesis of Lithium Alkyls

As I swerve back into the history of Organometallics I want to start back to 1917 in Germany.  A chemist named Wilhelm Schlenk, at the University of Munich, determined how to synthesize organolithium compounds through a Transalkylation process coupled with organomercury compounds.  He came up with two different methods of synthesis, one where there is nothing attached to the Lithium in the beginning and then the other method where there is an organic group that is transferred to the Mercury with a shorter alkyl group.  Both reactions are seen here below.

2Li + R₂Hg → 2LiR + Hg
2EtLi + Me₂Hg → 2MeLi + Et₂Li

The synthesis of the dimethylmercury (Me₂Hg) can be found here.


Source: 

The Immortality of Science

Here is a quote by Max Planck, touching on the subject of important scientific breakthroughs:

A scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die and a new generation grows up that is familiar with it.

4/18/2012 - How the Atomic Makeup of Water was Discovered

The question of how did someone could find out what is in water is a simple one, it basically consisted of combining hydrogen and oxygen together in a combustion to yield out water.  The scientist who carried out these experiments first was none other than Henry Cavendish, the British man to have the Cavendish Laboratory in Cambridge to be named after, of which many famous physicists go through, including Paul Dirac, James Maxwell, and Ernest Rutherford.  Now at that time, he had not named these gases as Hydrogen and Oxygen, but rather dephlogisiticated air and phlogiston respectively.  Phlogiston being the fire element that is released during combustion.  Through many experiments he determined that the greatest efficiency of water was obtained through the use of two parts hydrogen gas with one part of oxygen gas.  This was a very skeptical idea at the time that water was produced out of two invisible gases, but he endured many more of his experiments to prove his hypothesis, and win respect of the skeptics.

2H₂ + O₂ → 2H₂O + Heat

Source: Jaffe, Bernard. Crucibles: The Story of Chemistry. London, Hutchinson's scientific and technical publications, 1931.

4/17/2012 - The First Synthesis of Ammonium Chloride

The first recorded synthesis of this ammonium chloride compound was performed by Joseph Priestly, the minister responsible for my last post.  This was done while he was again experimenting with various gasses, and this time he was working with ammonia, seeing what would happen if he collecting a gas over mercury given off by ammonia water.  This gas was colorless, but contained the most pungent odor, so he took it even further by bringing the ammonia gas together with the hydrogen chloride gas.  This reaction produced a cloud, which after a while settled to form an odorless white powder.  He came to terms that this was something new when he analyzed it and noticed that there was no pungent odor from either the ammonia, nor the HCl.

NH_3(aq) + HCl_(aq) → NH₄Cl_(aq)

4/12/2012 - Creation of Soda Water

     In the late 18th century a Chemist by the name of Joseph Priestly, an self educated man living in Birmingham at the time, had an everlasting love for science and chemistry, so he decided to pursue science over his current ministerial work.  He was strong on the experimental method and had his scientific love focused on gases and the sources of the gas.  One day when he was at a public brewery he noticed the bubbles coming out of the vat and thought to himself what this gas was, so he decided to see what would happen if he would put a flame near these gases and observed that the flame extinguished after exposure.  So he collected this gas, and figured out a way to make it at home to analyze it, and little did he know that this gas was in fact carbon dioxide, CO2.  In one experiment he bubbled it through water and noticed that it was slightly soluble, and the water turned into an exceedingly pleasant sparkling water, very much like Seltzer water.  This was brought to the attention of the Royal Society and later became known as Soda water

4/10/2012 - Synthesis of Ethylene

     A very simple organic compound named ethylene, C₂H₄ was first synthesized by the ancient alchemist named Johann Becher. This compound of two carbons, containing a double bond was first synthesized by a process called ethanol dehydration where absolute ethanol is passed over a concentrated solution of sulfuric acid in the reaction C₂H₅OH + H₂SO₄ → C₂H₄ + H₂O +HSO₄. This compound later was introduced in 1922 as an anesthetic by Dr. Lockhardt, and is used today for hundreds of other purposes.

Beginnings of Chemistry: Paracelsus

   This post is a divergence from my usual reaction of the day, and more of a history lesson on one of the founders of what science is today, named Paracelsus.  Paracelsus was born in 1493 into an age of alchemy, where most men of that science were striving to turn anything into the valuable element of gold.  So naturally, as a man in love with the natural world, he would be immersed into the world of science (alchemy, medicine, astronomy, and botany).  In a lifetime of chasing this witchcraft and non scientific method of medicine, he finally had his epiphany in seeing that there were better methods in the science of medicine.  He found that it was better to search for drugs, to then prepare and purify them for use, than to use the previous methods of healing.  An example of this was that he was the first to make a tincture of opium, which was named by him laudanum, where he determined that the opium alkaloids were more soluble in alcohol than water and resulted in him making this laudanum solution.  At first people were skeptical of him because of his title as alchemist, meaning that he was related to the history of alchemists failing at producing gold.  Because of this he found it his mission to change peoples opinions of alchemy and science.  He gives a beautiful quote, that has much relevance still today for science skeptics:

"It's name will no doubt prevent its being acceptable to many; but why should wise people hate without cause that which some others wantonly misuse? Why hate blue because some clumsy painter uses it? Which would Caesar order to be crucified, the thief or the thing he had stolen? No science can be deservedly held in contempt by one who knows nothing about it.  Because you are ignorant of alchemy you are ignorant of the mysteries of nature."

     In changing the mission of the 16 century alchemist, he also set out to change the methods of the physician stating clearly that "if the physician were not skilled to the highest degree in alchemy, all his art was in vain".  With today's sciences we see clearly that he set future scientists in the right direction, and produce technology to better the human race.

Source:
Jaffe, Bernard. Crucibles: The Story of Chemistry. Hutchinson's Scientific and Technical Publications, London, 1931

3/26/2012 - Synthesis of Arsphenamine

     At this point in time, in 1909, medicine was very limited on what cured versus what merely treating a disease, and there were many breakthroughs in this field all of the time.  A year prior to this date a man named Paul Ehrlich invented the chemotherapy method in fighting cancer through using toxic compounds.  With his knowledge of toxic material he was experimenting on what other diseases could be helped through this method and he synthesized a molecule called Arsphenamine, or also known as Salvarsan, used to treat syphilis.  It was found through synthesizing hundreds of organic arsenical compounds and testing each one.  This was also the first organic antisyphilic, meaning that before this compound was produced, syphilis was only treated with inorganic compounds such as Mercury.