09Feb 2018 by Vincent Summers No Comments

Capillary Action from the Forces of Adhesion and Cohesion

Chemistry, Plants
What is capillary action? The easiest way to define it is to give the simplest example of it at work. A capillary is a tube with a fine bore, typically less than a millimeter. For the purpose of our discussion, we will use a scientist's glass capillary tube, which is both straight and clear. The liquids we will discuss as examples are water and mercury. Not All Liquids Exhibit Capillary Action Take note of Figure 1. Two capillary tubes (not drawn to scale) are immersed in liquid – the left tube in water, the right in mercury. The water rises up its tube and forms a concave meniscus at top. The mercury does not rise up its tube. It forms what looks like the upper portion of a sphere –…
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29Jan 2018 by Vincent Summers 1 Comment

Converting Gas Temperature to Particle Velocity

Chemistry, Physics
[caption id="attachment_18761" align="alignright" width="440"] Atoms or Molecules of Gas[/caption] Unlike liquids or solids, whose atoms or molecules have greater correlation with each other, gas atoms and molecules move somewhat independently of each other. This is to be expected. A gas occupies a much greater volume than a corresponding liquid. This independent behavior allows us to calculate the root-mean-square velocity of gas particles directly from temperature. Tweaking the Ideal Gas Law We derive this equation from another well-known equation, the Ideal Gas Law equation. Algebraically, that equation is written: PV = nRT where P is pressure, V is volume (not velocity), n is the number of moles of gas, R is the ideal gas constant and T is the temperature. By combining the above equation with derivatives of Boltzmann's equation, we…
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17Jan 2018 by Vincent Summers 3 Comments

What Went Wrong? Preparing an Alkyl Halide

Chemistry, Entertainment
[caption id="attachment_18523" align="alignright" width="440"] Reflux and distillation apparatus.[/caption] Preparing an alkyl halide was one of the earliest of my home lab experiences. First, allow me to give you a little background. In the 8th grade, we were instructed by our English teacher, Mrs. Best, to write a career report about our intended future employment. My guess is most of us had not thought about that. At least I hadn't. So I chose astronomy. I mentioned this to Mom. "No," she said, "you will not become an astronomer. Astronomers don't make any money." I tried to talk her out of it, but eventually I gave up. "Chemistry," I said. Mom agreed that was acceptable. One of her friends had a chemistry background. So in the '70s I obtained my BS in…
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13Dec 2017 by Vincent Summers 1 Comment

What IS the Kinetic Isotope Effect and How Is It Useful?

Chemistry, Physics
[caption id="attachment_18280" align="alignright" width="460"] The simplest atom.[/caption] Matter and the atoms that make it up consists of electrons, protons, and neutrons. The center or nucleus of each atom consists of at least one positively charged proton. Usually the nucleus includes neutrons, which are uncharged. Negative electrons are found in orbitals well outside the nucleus. Their number equals the number of protons in the nucleus. Such atoms have a net charge of zero. Elements The number of protons determines what element an atom is. One proton identifies hydrogen, two protons helium, three lithium, four beryllium, five boron, six carbon, and so on. Each of these elements possesses a unique chemistry. The quantity of protons equals the quantity of electrons, so everything's set, right? Well, no! The number of neutrons in all…
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05Jun 2017 by Vincent Summers 7 Comments

Lemon Chemistry: Flavor and Aroma Profiles

Chemistry, Food
To detect aroma, airborne chemicals must enter into our nasal passages. Volatile aromatic oils carried in when we breathe, interact with receptors located along those passages. Though flavor is somewhat influenced by our sense of smell, flavor primarily requires substance solubility in order to reach the different kinds of receptors located in various parts of the tongue. Let's explore a little lemon chemistry. Lemon Chemistry: Flavor The tongue detects four, perhaps five, flavors. They are sweet, salty, sour, and bitter. Some add savory1. There can be no doubt the primary taste of lemon is sour. Mention sour and the organic chemist thinks of organic acids. Lemons are rich in three organic acids: citric, malic, and ascorbic (AKA Vitamin C). Citric acid predominates. Suck on citric acid and you’ll think of…
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03May 2017 by Vincent Summers No Comments

Calculating Quantities for Stoichiometric Chemical Reactions

Chemistry, Education
[caption id="attachment_17791" align="alignright" width="380"] Image CCA-SA3.0 Unported by Lord Mountbatten[/caption] Exam time approaches and you realize your teacher is likely to write down some equations and expect you to fill in the blanks. So you would like to consider a few problems ahead of time to prepare you in advance. We will demonstrate two. The second problem is just a bit tricky. See if you can anticipate what gives! Problem 1: We will first consider the reaction of sodium hydroxide (NaOH) plus hydrochloric acid (HCl) to yield sodium chloride (NaCl) plus water (H₂O). NaOH + HCl → NaCl + H₂O Only one molecule of each reactant is needed to produce one molecule of each product. 1 NaOH + 1 HCl → 1 NaCl + 1 H₂O The atomic weights for…
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26Apr 2017 by Vincent Summers 2 Comments

Benzene from Coal and Lye?

Chemistry, Education
[caption id="attachment_17736" align="alignright" width="480"] Coal and Lye[/caption] As a youth, I read whatever chemistry books I could get hold of. One made reference to an obscure synthesis of the liquid aromatic compound benzene from coal and lye, by means of heat. This reaction would seem to be an improbable one. Can a stoichiometric equation be written for such a synthesis? The answer is, Yes. This in itself does not guarantee the reaction can actually take place. 6 NaOH + 9 C → 3 Na2O + C6H6 + 3 CO I learned of this synthesis from an old book, possibly published in the 1800s. Coal and Lye - What Conditions? Such a reaction strongly suggests isolation. The reaction required considerable heat. Also, air was to be excluded, since carbon would react…
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20Apr 2017 by Vincent Summers 2 Comments

Cuprous Sulfate: A Disagreement with My High School Chemistry Teacher

Chemistry, Education
[caption id="attachment_17698" align="alignright" width="440"] Classroom[/caption] As a kid, I was excessively shy and retiring – except when it came to matters of science and math. When it came to them, I was generally quiet but I could become quite outspoken if the occasion arose. During senior year, I approached my math instructor and told him an entire chapter in our textbook was wrong. He was reluctant to hear me out, but when he did, he acknowledged I was correct. On one occasion during junior year, I was listening to my chemistry teacher attentively when he spoke of cuprous sulfate. For those who are unacquainted with terminology, this would have been the old name (the name I still use) for copper(I) sulfate. I informed Mr. D’Alesandro that the only existing copper…
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19Apr 2017 by Vincent Summers 2 Comments

I Follow Dmitri Mendeleev’s Recipe for Chromyl Chloride Preparation

Chemistry, History
[caption id="attachment_17682" align="alignright" width="380"] Chromyl chloride. - Image by W. Oelen CCA-SA3.0 Unported[/caption] When I was young, I’d sign out chemistry books from three libraries. One of these was the local public library. Another was my high school library. Yet another favorite library was the one at Franklin Institute in Philadelphia. A special favorite book was a thin, early volume featuring the writings of Russian chemist, Dmitri Mendeleev (1834-1907). That volume was published in the late 1800s. Its pages were old—its recipes enticing. One of those recipes was for the making of a compound of the element chromium, a red-brown volatile liquid. A chromyl chloride preparation! I would learn first hand what it was like. But I needed some specialized laboratory equipment and supplies. I needed a retort, a burner,…
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