Phases of Matter XI - Suspensions
Written by Translator on July 30, 2008 – 10:51 pm -Crossposted at Dailykos.com
It has been a while since I added to this series. For this discussion, only the “classic” phases of matter (solid, liquid, and gas) will be covered. That gives, for binary systems, the following possibilities:
Solid in solid suspensions
Solid in liquid suspensions
Solid in gas suspensions
Liquid in solid suspensions
Liquid in liquid suspensions
Liquid in gas suspensions
Gas in solid suspensions
Gas in liquid suspensions
Gas in gas suspensions
A suspension is defined as a material, on a level larger than single molecules, ions, or atoms, dispersed in a homogeneous manner in another material. Thus they differ from solutions, where the material dispersed in on a molecular or smaller scale.
Tags: Colloid, Mixtures, Phases of matter, Suspensions, Teaching
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Phases of Matter X - Elements, Compounds, and Mixtures
Written by Translator on July 3, 2008 – 8:00 pm -Normal matter (not exotic matter like black holes or neutronium) is either an element, compound of two or more elements, or a mixture of elements, compounds, or both. This sounds pretty basic, but is important and will be needed for future installments.The classic definition of an element goes something like, “a material that cannot be decomposed into simpler materials”. That is pretty good, but a more fundamental one is that an element is a material composed of atoms that all have the same atomic number. (The atomic number is the number of protons in the nucleus). This is a better definition because we now know that we can fission uranium, for example, into simpler elements.
Elements come in several varieties, called isotopes. While atoms in an element all contain the same number of protons, they can differ in the number of neutrons (uncharged particles, protons have a single positive charge). Only one stable element has no neutron in its nucleus, and that is the common isotope of hydrogen, the nucleus of which consists of a single proton. Another isotope of hydrogen, called deuterium, contains a proton and a neutron, while a third isotope, tritium, contains a proton and two neutrons. Tritium is radioactive and must be produced artificially. One way that can be done is to bombard lithium with neutrons. This is how thermonuclear bombs work.
Tags: Compound, Element, Mixture, Phases of matter, Teaching
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Phases of Matter VIII - The Wonder of Water 1
Written by Translator on June 30, 2008 – 9:41 pm -Crossposted at Dailykos.com
None of us should be alive. We are only because of water. Water. Everyone knows about it, everyone uses it, but few understand it. Every schoolchild knows that water is H20, but few scientists realize the ramifications of that simple formula.
Water has a molecular weight of 18 atomic mass units (amu, the mass of a proton or neutron, roughly) since the common isotope of oxygen has a a mass of 16 amu, and that of the most common type of hydrogen has a mass of one amu.
Water looks sort of like Mickey Mouse, in that the two hydrogen atoms make an angle through the H-O-H bond of about 104.45 degrees.
Water, at 18 amu, should be a gas. Nothing with that molecular weight is a solid except for lithium, and it is a metal, and metallic bonds are special. I wrote about that earlier in this series.
All of the atmospheric gases weight more, on a molecular basis, than water. Ammonia, water’s close cousin, is a gas at STP (standard temperature and pressure, one atmosphere at 20 degrees C). Both ammonia and water share a special property, but water does it better.
The secret is the hydrogen bond. It turns out, due to both electrostatic and quantum mechanical considerations, that hydrogen (the lightest and smallest element) when bonded to nitrogen, oxygen, or fluorine (the most electron hungry elements in the second row of the periodic table) is “special”.
We should all be dead, and water should not exist. But the hydrogen bond changes everything. More in future, if any interest. I will hang around a bit to answer comments and stave off flames. Warmest regards, Doc.
Tags: Hydrogen bonds, Phases of matter, Quantum Mechanics, Teaching, Water
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Phases of Matter VII - Plasmas
Written by Translator on June 27, 2008 – 5:25 pm -Crossposted at http://Dailykos.com
A plasma is a noncondensed, fluid state of matter, much like a gas. The difference between gases and plasmas is that gases are electrically neutral, while plasmas have had some, most, or all (depending on conditions) of its atoms separated from one or more electrons.
Thus, a plasma is mixture of ions (atoms missing one or more electrons) and free electrons. This makes them have some extremely useful properties, and we exploit those properties on a daily basis.
Tags: Fluorescent Lamp, ICAP, Ion Engine, Lightening, Phases of matter, Plasma, Teaching
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Phases of Matter V - Gases 1
Written by Translator on June 25, 2008 – 7:29 pm -Crossposted at Dailykos.com
Gases, like liquids are fluids, in that they have no definite shape, but take that shape of their container, be it a balloon, a pressure cylinder, or a gravity envelope. Unlike liquids, gases are not “condensed” in that their molecules have a much greater spacing than that of liquids or solids.
This spacing is on the order of around 1000 times more as a general rule of thumb. This makes it possible to compress gases, using energy to push the molecules closer together. The ramifications of this are huge, from air conditioning to energy transport to solar power storage.
Tags: Boyle's Law, Charles's Law, Combined Gas Law, Gases, Gasses, Gay-Lussac's Law, Ideal Gas Law, Phases of matter, Science, Teaching
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Phases of Matter IV - Liquids
Written by Translator on June 24, 2008 – 6:33 pm -Crossposted at Dailykos.com
Liquids share with the solids the term “condensed phase” matter, meaning that the density of solids and liquids is greater than gases and plasmas. The reason is that the molecules of matter in the condensed phase are much closer together than in noncondensed phases, due to energetics specific to the particular substance. Condensed phase materials are essentially noncompressible, because their molecules are already near as close together as they can be before repulsive forces dominate.
Tags: Boiling, Distillation, Liquid, Phases of matter, Teaching
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