Chemistry Archives - Page 7 of 22

16Apr 2019 by Vincent Summers No Comments

Ions are Stabilized by Spreading the Electric Charge

[caption id="attachment_23719" align="alignright" width="440"] This image depicts the spreading charge of a nitrate ion. Image by elpot[/caption] Ions are charged atoms or molecules. They may have a plus charge, a minus charge or – rarely – both. Examples of each are the positive sodium ion (Na+1), the negative bisulfate ion (HSO4-1) and the glycine zwitterion (or dipolar ion) (H3N+1‐CH2‐C(O)2-1). Spreading the electric charge will stabilize both positively and negatively-charged ions – but how does this work? Charge and Nature Even as “nature abhors a vacuum,” it likewise abhors a concentrated electric charge – lightning well illustrates this point. Although ordinary table salt exists in water solution as charged ions, those ions are not isolated as the above shorthand symbols would indicate. The ions are stable in water because the charge…

15Apr 2019 by Vincent Summers No Comments

Do the Acids in Coffee Bother You? Chlorogenic Acid and Derivatives

Chemistry, Food

Although there are a host of organic acids found in coffee, and a variety of factors, such as brew temperature and grind size, affect these acids, the chlorogenic acids and their roasting derivatives, the caffeic and quinic acids, stand out. What are these acids, and how do they play a definitive role in the coffee we drink? Coffee Chemistry: Chlorogenic Acid Chlorogenic acid (CGA) is a combination ester and acid derived from two acids: caffeic acid and quinic acid. These two acids each contain not only an acid group, but alcohol groups as well. A carbon atom plus two oxygen atoms and a hydrogen atom makes up the carboxylic acid group – we often write this as –COOH or –CO₂H. An alcohol group consists of an oxygen and a hydrogen…

15Apr 2019 by Vincent Summers 19 Comments

Rare Earth Metals – 17 Special Elements

Chemistry, Technology

[caption id="attachment_23646" align="alignright" width="480"] Rare Earths. Photo ARS-USDA by Peggy Grubb.[/caption] Most of us are familiar with elements – the building blocks of matter. Most of us know about elements such as oxygen, nitrogen, carbon, sulfur, sodium, and helium. Yet, there are other elements few have even heard of, despite their immense technological and medical importance. Are you familiar with the rare earth metals? Allow me to introduce them: what are they good for, and where do they come from? Rare Earth Metals Among the less commonly known elements are the rare earth metals. These elements have many important uses, such as: Rare earth metals are used in heat-resistant, powerful, permanent magnets. They are employed in superconductors for cryogenics applications. They are used in pyrophoric alloys for initiating combustion. And…

14Apr 2019 by Vincent Summers 1 Comment

Crown Ether Donut Holes Serve Special Purposes

Chemistry

[caption id="attachment_23625" align="alignright" width="480"] Assorted Crown Ethers[/caption] Crown ethers are designer molecules – ring structures intended to serve specialized purposes. Each ring contains a number of ether linkages (-C-O-C-) that, based upon their structural formulas as they are drawn on paper, give the appearance of a royal crown. The “crowns” have different “sizes.” The most common crown ethers sport ethyleneoxy groups (-CH2-CH2-O-) joined end-to-end (making these structures oligomers), which are closed like a necklace. Ring properties and rigidity may be modified by means of appendages on the ring or other hetero atoms along the ring. Simple crown ether rings such as those shown in the figure lack rigidity because every bond is single. There are no multiple bonds reducing flexibility. Crown Ether Nomenclature For the most common crown ethers, there…

13Apr 2019 by Vincent Summers No Comments

Organic Chemistry and Life: Has Vitalism Been Born Again?

Biology, Chemistry

[caption id="attachment_23607" align="alignright" width="480"] Pillars of Creation[/caption] The phrase ‘organic compound’ relates to the word organism, closely associated with life and life processes. Organic compounds largely consist of carbon atoms linked in chains or rings that contain hydrogen and frequently one or more other atoms called hetero atoms – notably oxygen, nitrogen, sulfur, and phosphorus. Inorganic compounds are everything else – for example, nickel chloride, ammonium nitrate, carbon dioxide, and phosphorus pentoxide. It is important to recognize that there are a relative handful of organic compounds that do not contain carbon chains or rings, but result from life processes, including for example, urea, NH2-CO-NH2.. During the 1800s, scientists widely believed organic compounds could not be generated in the laboratory. However, in the year 1828, chemist Friedrich Wöhler converted inorganic ammonium…

13Apr 2019 by Vincent Summers 1 Comment

Use of the Hull Cell in Maintaining Electroplating and Electroforming Baths

Chemistry, Electrical

[caption id="attachment_23592" align="alignright" width="480"] Hull Cell[/caption] Electroplating is the depositing of a metallic film onto a substrate, whatever form that substrate takes. One most unusual substrate is baby shoes! The electroplating industry contributes both functionally and aesthetically to a host of consumer products. Plating is both a science and an art. Electroplating bath chemistry is crucial. It is dynamic, ever changing. Frequent adjustments, tweaks, keep it in top operating condition. Plating Bath Components Every plating bath is different, but there are some components that are pretty standard for the majority of them. 1. Water 2. Metallic salt 3. An acid or an alkali version of the same salt as the metal 4. Brighteners 5. Anodes Example One example demonstrating the art-science dichotomy is the cyanide-copper flash bath, primarily used in…

13Apr 2019 by Vincent Summers 1 Comment

Amino Acids and Proteins: Major Components of Meat

Chemistry, Food

[caption id="attachment_23573" align="alignright" width="480"] Image by LifeisGood[/caption] The meat we eat largely consists of proteins, which are made up of amino acids. Proteins may be broken down into amino acids – and, amino acids may be built up into proteins. Consider the basic structure of amino acids and proteins. Amino Acid = Amine + Carboxylic Acid Amino acids contain an amino group, an acid group, and an alkyl group. In an amino group, there is one trivalent nitrogen atom, which is attached to two hydrogen atoms. We write out an amino group as –NH2. An amino acid also contains a carboxylic acid group. It is written –COOH, that is, it contains one tetravalent carbon atom that is double-bonded to an oxygen atom, and also it is single-bonded to one hydroxyl…

12Apr 2019 by Vincent Summers 3 Comments

The Fascinating Kitchen Physics of Boiling Water

Chemistry, Physics

[caption id="attachment_23534" align="alignright" width="480"] Image by Jeshoots[/caption] Cutting-edge science is fascinating. Yet the science of everyday life is anything but boring. Consider the simple act of boiling water on the kitchen stove. There are many factors that come into play leading to the production of steam. Let's take a close look at water as an individual molecule and as a cluster of interacting molecules. Water at the Molecular Level Water consists of one oxygen atom plus two hydrogen atoms. An atom of oxygen is much larger than one of hydrogen. Most hydrogen atoms consist of a lone electron in orbit about a single proton nucleus. Oxygen atoms have a much larger nucleus orbited by 8 electrons. Oxygen has a strong affinity for electrons. So it is an electronegative element. On…

30Mar 2019 by Vincent Summers No Comments

Chemical Explosives: Picric Acid and Picrates

Chemistry, Technology

Two common varieties of reaction are acid-base and oxidation-reduction (Redox). A typical acid-base reaction involves the conversion of the reactants (naturally, an acid and a base) into a salt plus water. We all are familiar with table salt, which is only one of many salts. Table salt can be made by reacting hydrochloric acid with the strong base sodium hydroxide: HCl + NaOH → NaCl + H2O The valence states of the reactants remain the same when they are transformed into the products. Hydrogen, chlorine, sodium, and hydrogen all stay at +1, while oxygen remains at -2. Oxidation-Reduction Oxidation-reduction reactions feature valence changes. For instance, consider the oxidation of carbon by oxygen... C + O2 → CO2 Each carbon atom (left of the reaction arrow) loses 4 electrons, while each…

14Feb 2019 by Vincent Summers No Comments

Was Mom Right? Is Eating Carrots Good for the Eyes?

Chemistry, Food

From childhood, Mom admonished me, "Eat your carrots! They're good for your eyes." Now, I wore glasses. Later, with Mom's approval, I became an organic chemist. Since I listened to Mom, I eat my carrots. In fact, with lots of butter and salt, I rather enjoy them! But throughout my youth, I always wondered if they really are good for our vision. Here's what I learned. Carrot Chemistry Carrots contain the organic compound β-carotene. It's chemical structure is seen in the image below. The chemical formula of β-carotene is C40H56. In addition to imparting the orange color to a carrot, if a molecule is split down the middle and the cleaved double bond is hydrated for both halves, the result is two molecules of retinol, C20H30O. See the image. Carrots…