formula model H CC H H Image sources b c

Formula model h cc h h image sources b c

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formula model H | / C==C / \ H H (Image sources: b) , c) ) , available online only to subscribers) The authors further report that “Finally, we were able to deflect a droplet stream of a nonpolar liquid (tetrachloroethylene),” the experiments for which are explained in the rest of the article. They further report in the article: The behavior of C 2 Cl 4 was particularly interesting. With a vigorously electrified balloon it was just possible to detect a very weak deflection in a C 2 Cl 4 stream even though this liquid is nonpolar. Brindle and Tomlinson reported that a strong deflection could be observed in a CCl 4 stream under conditions of low humidity ( 8 ); Vemulapalli and Kukolich ( 9 ) and Shakhashiri ( 10 ) observed deflection of benzene and n -hexane, respectively (attributed in ref 9 to forces on induced dipoles and in ref 10 to dielectrophoresis, the lowering of potential energy when a dielectric material moves from a region of lower to higher electric field). Given that the electric field near our charged balloon (ca. 10 cm radius) was only slightly inhomogeneous and that no deflection was observable in a strongly inhomogeneous field even for water in our re-creation of the Vemulapalli and Kukolich experiment when the droplets formed in an electrically screened region, induced charging, even of insulating liquids, seems to be the only general explanation for all of these observations. More on other demonstrations that are not quite what they seem “Dissolving” Styrofoam In this demonstration, the teacher will place copious amounts of Styrofoam™ peanuts or other Styrofoam™ packaging into a beaker containing acetone. The Styrofoam™ appears to “disappear” into the acetone, with some bubbling, while closer inspection shows that some opaque viscous liquid material still exists in the acetone at the bottom of the beaker. The usual explanation is that the acetone is “dissolving” the Styrofoam™. While this seems like a reasonable explanation, dissolving usually means the solute, the material being dissolved, truly disappears into the solvent, the material that is doing the dissolving. The fact that viscous liquid matter still remains in the mixture indicates that this is not a case of true dissolving. Styrofoam™ is the Dow Chemical Company trade name for expanded polystyrene (EPS). (We’ll explain the expanded part shortly.) Polystyrene (PS) is a long-chain polymer composed of many styrene monomers. Styrene, (C 8 H 8 ) n [at right: a) structural formula, b) space-filling model], is essentially a phenyl group (benzene ring) attached to an ethylene. Polystyrene is essentially a chain of ethylene reactive groups on which phenyl groups are alternately attached to the chain of carbon atoms in the ethylene groups. The polymer has the structural formula c) at right. The subscript “n” in the formula represents a large number of styrene monomers, perhaps a few thousand. 36
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The diagram below shows the polymerization of styrene, where the double bond in the
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