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Balancing Chemical Equations (Introductory Stoichiometry)
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A chemical equation describes what happens in a chemical reaction. The equation identifies the reactants (starting materials) and products (resulting substance), the formulas of the participants, the phases of the participants (solid, liquid, gas), and the amount of each substance. Balancing a chemical equation refers to establishing the mathematical relationship between the quantity of reactants and products. The quantities are expressed as grams or moles. It takes practice to be able to write balanced equations. There are essentially three steps to the process: 1.Write the unbalanced equation. •Chemical formulas of reactants are listed on the lefthand side of the equation. •Products are listed on the righthand side of the equation. •Reactants and products are separated by putting an arrow between them to show the direction of the reaction. Reactions at equilibrium will have arrows facing both directions. 2.Balance the equation. •Apply the Law of Conservation of Mass ...
Mercury Beating Heart
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The Mercury Beating Heart is a popular chemistry demonstration/experiment in which a blob of mercury is made to pulsate, resembling a beating heart. The mercury beating heart requires only a few materials and is easy to set up, though it's a little tricky to get going. Mercury Beating Heart Materials •drop of mercury •dilute sulfuric acid (battery acid strength works) •potassium permanganate or potassium dichromate solution or crystals •iron wire or nail •watch glass or petri dish Perform the Mercury Beating Heart Demonstration 1.Place a drop of mercury into a dish. 2.Cover the mercury with sulfuric acid. 3.Add a small amount of potassium permanganate or potassium dichromate. 4.Slowly move the iron wire or nail so that the tip is near the mercury, but not quite touching it. The distance depends on the ratio of the concentration of the acid and oxidizer, so you'll need to play with this to find the sweet spot. 5.Once you have the distance right, th...
On This Day in Science History - September 22 - Isotopes
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September 22nd marks the passing of Frederick Soddy. Soddy was an English chemist who investigated the assortment of newly discovered elements that were decayed from radium, thorium and uranium. At this time, many of these elements had names like mesothorium, Radium A, B, C, D, E, F and Uranium X, each with a different half-life. Chemists were trying to separate elements like radiothorium from thorium but could not accomplish the task. Soddy theorized they were all the same elements and could not be separated chemically. They had slightly different atomic masses, but were the same elements. He gave the name 'isotope' to the atoms in this elemental mixture. He cited radium D and thorium C were actually two different isotopes of lead and acted the same as lead chemically. He couldn't explain his theory with the current science. When the neutron was discovered by James Chadwick, Soddy's isotope theories suddenly made more sense. He also described the mechanics of radioac...
Can You Balance an Egg on the Equinox?
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The autumnal equinox is Wednesday, September 22nd, 2010. This is the first day of fall in the northern hemisphere, or the first day of spring in the southern hemisphere. Are you familiar with the urban legend that it's easier to balance an egg on end on the equinox than on other days of the year? Test it and see! The autumnal equinox one of the two times during the year when the sun crosses the celestial equator and the spin axis of the Earth points 90 degrees away from the sun. Why should this affect your ability to balance an egg on end? The premise is that aligning the gravitational pull of the Sun with that from the center of the Earth should somehow make it easier to balance any object. Test the Egg-Balancing Hypothesis Yourself Take a carton of eggs and try balancing the eggs on end today. Can you stand any of them up (without resorting to tricks like putting salt under the eggs)? Can you stand eggs on their small ends as well as their large ends? Keep track of your re...