Why Some Sugars Have a Cyclic and a Chain Structure

Chemistry, Education
In your current course of organic chemistry, you're studying sugars. You notice in a text or see on the web a particular sugar, you've searched for by name. What is its true structure? You see it drawn as a chain structure with pendant groups. As you read about it, you see reference to another structure... a cyclic structure! What gives? Sugars: Example Fructose Some chemicals undergo change with the most minimal modification of environment. One example is keto-enol tautomerism. Fructose and certain other sugars experience something similar. It reacts reversibly, to form two cyclic hemiketals. Fructose Hemiketals A hemiketal forms by combination of an alcohol group with a ketone group. Fructose supplies both reactive groups, internally. For the generic reaction for hemiketal formation, see the accompanying illustration. Note the presence…
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Carbide Cannons & Miners’ Lamps – The Chemistry?

Chemistry, Technology
When I was a kid, a friend showed me what he called an acetylene cannon. Many know it as a carbide cannon. What made it work? It's all a matter of chemistry. Which Carbide? A carbide is a compound in which carbon is bonded to a more electropositive element. Silicon carbide (SiC) and tungsten carbide (WC) are two well-known examples. What carbide do carbide cannons use? Calcium Carbide The answer is calcium carbide. Lime and coke are placed in an electric furnace. The chemical reaction is: CaO + 3 C → CaC2 + CO2↑ What makes calcium oxide so interesting is its bonding. The valence of calcium is +2. Ordinarily, carbon is assigned a valence of 4. Something's strange here... The puzzle is solved if we write the structure of…
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Artificial Butter Flavor – Just a Product of the Chem Lab?

Chemistry, Food
You are crunching away at some tasty munchable. Since you're not doing anything else and would like to prove you can do two things at once, you turn the bag/box around and read the ingredients. Yes, yes, oh that! And yes, yes, ah. What's that? Artificial Butter Flavor? What's artificial butter, the product of artificial cows? What Is Artificial Butter Flavor? Simply put, the expression "artificial butter" refers to taste and use, rather than to any single, particular ingredient. A Simple Compound Diacetyl is considered to impart a buttery flavor to foodstuffs. As the illustration shows, diacetyl is a small, simple molecule. Writing it out in full, it is... CH3(CO)(CO)CH3 Note the similarity to two acetic acid (vinegar) molecules... CH3(CO)–OH + HO–(OC)CH3 [sc name="MidArticleAdsense"] Synthesis The second image depicts one…
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Alkene Isomers and Nomenclature: 1,3,5-Hexatriene

Chemistry
Many moons ago, chemistry was divided into two large groups, organic chemistry and inorganic chemistry. Organic chemistry was thought to be the 'chemistry of life'. This was because a mysterious "vital force" associated with life was thought essential to produce organic compounds. Most organic compounds consist of carbon and hydrogen atoms, with or without nitrogen, oxygen, phosphorous, or other atoms. We will discuss a simple hydrocarbon. A hydrocarbon consists solely of carbon and hydrogen. Hydrocarbon Bonds Carbon and hydrogen usually bonds in one of three ways: single bonds (-), double bonds (=), and triple bonds (≡). In this article, we will feature only single and double carbon-to-carbon bonds... two single and three double. The compound is 1,3,5-hexatriene. Notice the featured image (above) that illustrates the most common way it is…
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Adenosine Triphosphate (ATP) and Metabolism

Chemistry
In discussing the chemistry of the human body, the media features many important substances. Take water. We are told how important it is to drink lots of water. Our body cells do consist, after all, of about 60% water. And we repeatedly hear of DNA, cholesterol, free radicals, omega fatty-acids, trans fat and sodium. Yet, there is one essential compound that is seldom mentioned... adenosine triphosphate, acronym ATP. Have you heard-tell of ATP? No? Yet it is remarkably important – you could not exist without it. Besides, even if you could, the energy you'd need to function would be totally unavailable. ATP - What Is It? ATP, on examination (see image) is one molecule consisting of three portions. There is an adenine portion attached to a ribose (sugar) portion, attached…
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Anodizing Aluminum: How Can It Be Done?

Astronomy, Chemistry, Technology
Aluminum is a versatile metal, yet in order to be used in certain applications, it needs to be modified, improved. One way of modifying it is to add certain ingredients, such as a trace of copper, to toughen it. Another modification is the process of anodizing aluminum. What does that refer to? Anode & Cathode We're all familiar with electroplating. We may have eaten meals using silver-plate utensils. Or we may have attended a classic auto show in which older cars have chrome-plated bumpers. A metal coating (plating) from a chemical bath is applied using electricity to transfer the metal from a supply source (the anode) to the object to be plated (the cathode). The simplified artwork below illustrates a copper bath, complete with anode, cathode, and plating solution. A…
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Explosives: Nitrogen-Containing Fulminates

Chemistry
Chemical explosives are unstable¹ solids (occasionally liquids) that decompose rapidly, releasing large quantities of gas. The sudden volume increase pushes violently against whatever contains the explosive, reducing it to shrapnel and releasing a thunderous noise. Many explosives are nitrogen-containing substances, such as trinitrotoluene (TNT), nitroglycerin, and the picrates. Additional historic explosives include the fulminates, and yes, fulminates contain nitrogen as well. The most famous fulminate is mercuric fulminate, officially named mercury(II) fulminate. Its chemical composition is, Hg(CNO)2 It consists of one mercury atom and two atoms each of carbon, nitrogen, and oxygen. In greater detail, it can be written, Hg+2(C≡N=O)2 or Hg+2(C≡N+–O-)2 Do Fulminates Remind You of Other Chemicals? Perhaps the anionic fulminate ion, –CNO- reminds you of the cyanate anion, –OCN- or isocyanate anion, –NCO? And well it should,…
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A Simple Valence Problem for a Beginning Chemistry Enthusiast

Chemistry, Education
It is not unusual for school systems to introduce students to chemistry by means of the Periodic Table of the Elements. The table is then broken down into sections: the metals, the non-metals, and the gases. Before long, the structure of the atom is discussed, including protons, neutrons, electrons, orbitals, shells, and valence. It is the last of these we will briefly discuss here – valence. First a very brief discussion, followed by examples, followed by a puzzling problem (to impart insight). Valence: A Simple Discussion Atoms, although containing positive protons and negative electrons, have a net charge of zero. They are electrically neutral. This means each lone atom has a number of electrons equal to its number of protons. For instance, a sodium atom¹ has 11 protons. It also…
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Tires to Lemons – Well, Not Exactly

Chemistry, Technology
Although individuals and governments fall far short of maintaining Earth's pristine qualities, many do desire to minimize waste and its first cousin, pollution. Although one admirable action would be to minimize production, another is to recycle the resultant wastes. The late 19th and early 20th centuries introduced industrialization, and with it mechanization. Part of the mechanization was the automobile. And part of the automobile was the automobile tire. Tires are constructed of rubber or rubber-related products. They wear out well before most automobiles wear out. The problem is: what to do with all those worn-out, used tires? Millions and millions of them. They do not readily break down on being exposed to the elements. How can they be recycled? One Problem with Tires Now What might happen if tires were…
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Chemistry Students: Remember the Water of Crystallization

Chemistry, Education
[caption id="attachment_24966" align="alignright" width="480"] Don't forget the water.[/caption] Chemicals are, for the most part, categorized into inorganic compounds and organic compounds. The expression "water of crystallization" is rarely applied to organic compounds, since most of them are not water soluble, and if they are, few even of those form crystals with water. What IS Water of Crystallization? A high percentage of water-soluble inorganic salts form crystals that include water in their crystal lattice. An example of a salt, with and without water of crystallization is cupric sulfate.¹ Such salts, deprived of water content, are termed anhydrous. In our example, we might speak of copper sulfate anhydrous.² Quantity of Water [caption id="attachment_24967" align="alignright" width="380"] Fine crystals of copper sulfate pentahydrate.[/caption] Hydrated copper sulfate includes 5 molecules of water in its crystalline…
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