13May 2016 by Vincent Summers 4 Comments

Is Cyclopropenone Aromatic or Not?

Chemistry
Is cyclopropenone aromatic? Before reading on, try to anticipate the answer to that question. When most students think of aromatic, they think of simple hydrocarbons—compounds composed of hydrogen and carbon atoms only. The best known example of an aromatic hydrocarbon is the 6-sided cyclic compound benzene—C₆H₆. Benzene, if drawn according to classical structures, has alternating single and double bonds between carbon atoms. Basic Qualifications for Aromaticity A double bond consists of one sigma (σ) and one pi (π) bond. If the ring is single rather than multiple (as, for instance, for naphthalene, which is comprised of two fused rings), and if it has 4n+2 completely conjugated π electrons in a closed loop or ring, is neutral, and is flat, the structure obeys Hückel’s rule and will be aromatic. There are…
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09May 2016 by Vincent Summers 1 Comment

Ethane Sigma Bond Rotation Conformers

Chemistry
[caption id="attachment_14316" align="alignright" width="440"] Methane Ball & Stick Model[/caption] Methane is the smallest molecule consisting of just carbon and hydrogen, CH₄. The second smallest hydrocarbon is ethane, C₂H₆. It is sometimes written H₃C–CH₃. The “dash” between the two carbon atoms represents a single bond. It is also a sigma bond. What is a sigma bond? And what are ethane sigma bond rotation conformers? What is a Sigma Bond? The carbon to carbon single bond is a covalent bond. That is, bonding electrons lying between the two carbon atoms are shared equally. A sigma bond is the strongest variety of covalent bond. The two atoms overlap head-on. One could view such a bond as being of cylindrical symmetry or like a straight line between the two atoms. Hence, the dash notation.…
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06May 2016 by Vincent Summers 1 Comment

Carbs or Carbohydrates – What are They?

Chemistry, Food
[caption id="attachment_14302" align="alignright" width="440"] Yum! White Potatoes.[/caption] When people refer to limiting their “carb” intake, they mean they are holding back from eating food rich in carbohydrates. What are carbs, and what are some examples of foods high in carbohydrates that dieters may wish to limit their consuming? Derived from carbo- (carbon) and hydrate (water), these substances are compounds such as sugars, starches, and cellulose that contain carbon, hydrogen, and oxygen. The ratio of hydrogen to oxygen atoms is 2 to 1, the same as that for water (H2O). In essence, all carbohydrates are some combination of carbon and water. What are Carbs – Sugars Mention sugar, and the average person thinks of ordinary table sugar or sucrose. Others may have also heard of glucose. This sugar is of special…
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05May 2016 by Vincent Summers 3 Comments

Cyanides How Toxic Are They? Are All Cyanides Deadly?

Chemistry, Medicine
Potassium and sodium cyanides are iconic poisons. Murder mystery movies frequently feature one of these two substances as the cause of death. Their chemical formulas may be written more than one way. Most simplistically, they are KCN and NaCN. K stands for potassium (kalium), and Na stands for sodium (natrium). C is for carbon. N is for nitrogen. Another way of writing the chemical formulas of these substances is, K–C≡N and Na–C≡N. Both of these chemical compounds dissolve in water. This makes them especially dangerous, since if consumed, they can enter the bloodstream and travel to all of the bodies’ cells. KCN → K+ + CN- NaCN → Na+ + CN- Cyanides How Toxic? Organic Nitriles Organic nitriles are a kind of cyanide. For instance, acetonitrile is written, CH3CN But…
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20Apr 2016 by Vincent Summers 4 Comments

Does Glass Flow? Is Glass Liquid or Is It Solid?

Chemistry, History
[caption id="attachment_14158" align="alignright" width="440"] Old glass (top); new glass (bottom).[/caption] From childhood, I had been told (and believed) that glass is a liquid. Kids are so trusting! I never doubted what the grown-ups were telling me was gospel truth. Well, is it the truth? Is glass liquid or solid? The answer is (and I say this almost sadly) glass is a solid. Is Glass Liquid Kids may be gullible, but adults should not be. They should know better. So the idea that glass is a liquid—where did the adults get that from? On what evidence was it based? It came from the belief that glass flows. "Evidence" did seem to suggest it. What evidence? [sc name="MidArticleAdsense"] The evidence of the windowpanes. I’m not sure how easy this is to check…
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18Apr 2016 by Vincent Summers 2 Comments

Ideal Gas Law Molecular Weight

Chemistry, Physics
Physics uses simplification to arrive at quick, moderately accurate answers for problems. Small friction sources and tiny masses may be discounted. In textbooks students are introduced to massless strings and frictionless pulleys. For chemists, there is no single equation that conveys the behavior of every gas. Still, the basic properties gases do share in common are combined to produce the simplistic equation of state. We will use this equation to determine the ideal gas law molecular weight. Deriving the Ideal Gas Law When we compress a gas, its volume shrinks. That is, the pressure is proportional to the inverse of the volume. P ∝ 1/V This has been known for hundreds of years as Boyle’s Law. In addition, as temperature increases, gas volume increases (think hot-air balloon). T ∝ V…
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11Apr 2016 by Vincent Summers 10 Comments

Vanilla and Vanillin: What’s the Difference?

Chemistry, Food
[caption id="attachment_14041" align="alignright" width="440"] Drying vanilla beans.[/caption] Probably the average grocery shopper is unaware there are two sources of the flavor of vanilla. They are vanilla and vanillin. Are they the same? Are they different? If they are different, what is that difference? Vanilla and Vanillin Historically, our favorite ice cream flavor has been vanilla. To draw special attention to the use of natural rather than synthetic ingredients, some have added descriptors to their ice cream. They use phrases like natural vanilla or natural vanilla bean. The vanilla bean comes from an orchid, and is completely natural. The flavor extract made from it is called vanilla. Yes, the word that ends in an “a,” and not an “n.” We still have vanilla and vanillin. So what is vanillin? [caption id="attachment_17377"…
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11Apr 2016 by Vincent Summers 3 Comments

Why Chocolate Truffle Centers Cool the Tongue

Chemistry, Food
[caption id="attachment_14026" align="alignright" width="480"] Yum! Chocolate Truffles.[/caption] A chocolate truffle may be a hollow sphere of hard chocolate filled with a special sort of chocolate filling. The filling inside melts in a unique way. When you put a truffle in your mouth, the inside chocolate cools your tongue. Is that really possible? Yes it is. It is not merely a psychological effect. Chocolate truffle centers really do cool the tongue. Chocolate Truffle Centers Cool the Tongue When the truffle is put into the mouth and the lips close around it, energy comes from the cheeks, the palate, and especially the tongue. The temperature of the tongue generally remains nearly constant and is higher than that of the truffle's center. The outer chocolate of the truffle dissolves away slowly. The center…
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01Apr 2016 by Vincent Summers 26 Comments

Devils Dice – What Are They?

Chemistry, Geology
[caption id="attachment_13950" align="alignright" width="380"] Peruvian Striated Pyrite - Rob Lavinsky iRocks.com CCSA3.0[/caption] I was in my 30s when I first heard of Devils Dice. What are they? I was raised in New Jersey. At the age of 33, I moved to Virginia. This short north-to-south emigration exposed me to certain speech, food, and culture changes. It took me a month to get over the accent. During that time, my brain adjusted and the accent sounded totally normal to me! I missed scrapple a lot. Since then, I’m happy to say scrapple successfully has invaded the south. But there were other changes as well. In the south, there are buzzards. There are red bud trees. There are ABC stores! Even the ground itself offered something new. There is this kind of…
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25Mar 2016 by Vincent Summers No Comments

Nitrocellulose Motion Picture Film Decomposition

Chemistry, Technology
[caption id="attachment_13904" align="alignright" width="440"] Film Decomposition - Library of Congress[/caption] If you’re like me, you enjoy not only some of the more modern offerings of the motion picture industry, but many of the gems from the golden era. Sadly, some excellent productions are either damaged or lost due to nitrocellulose motion picture film decomposition. Nitrocellulose Motion Picture Film Motion picture films incorporate an emulsion atop a “plastic” substrate. Historically, this substrate has been made from three basic materials. The oldest of film varieties was cellulose nitrate, a.k.a. nitrocellulose. Films produced using this material were, and are, the most susceptible to loss through deterioration. It’s a matter of chemistry. Chemical Structures Notice the structure of cellulose, a major component of plant fiber. Then examine the largely similar structure of nitrocellulose. Take…
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