Texas ABM Univwsity College Station. TX 77843
More "Quickies" Milton H. Rosenberg Pace University-Westchester Campus Pleasantville,NY 10570
1) Fluorine is an extremely reactive element. Even some of
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the "noble" rases combine with fluorine. Yet there is a whole class f; substances with which fluorine does not react. What are these substances? The continuing addition of a solute to its solution usually results in a saturated solution in contact with some undissolved solute (a cundition of dynamic equilibrium between dissolved and undissolved species). However, with some solutes and solvents, it is impossible to prepare saturated solutions. Give an example of such a case. Barium chloride is a deadly poison, but barium sulfate is administered orally (or sometimes by another route) for X-ray examinations of the gastrointestinal tract. Mercury(1) chloride (Hg~C12)has been used safely as an oral medication for certain problem conditions, but mercuiy(I1) sulfate is a deadly poison. Explain these facts. An aqueous solution of ClOH (more usually written as HOCI) is acidic, while an aqueous solution of NaOH is alkaline (basic). Why does the H to 0 bond breakpreferentially in ClOH rather than in NaOH? Certain axioms and basic principles of mathematics seem to be contradicted in chemistry. Can you give chemical examples that appear to "violate" the following mathematical statements? a. The whole is equal to the sum of its parts. h. A B = B A (the Commutative Law for Addition) c. (A B) C = A (B C)(the Associative Law for Addition) d. 1 + 1 = 2
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Answers (1) Fluorides. (2) Any pair of mutually miscible liquids, such as ethanol and water. (3) Neither chloride nor sulfateions are poisonous at moderate concentrations, but barium ion and mercury ions are poisonous. Bas01 and Hg~Clzare too insolubleto provide a dangerous concentration of barium or mercury ions (althoughsame individuals are sensitive to Ba2+ concentrations as low as that in saturated BaSOa). Both BaClz and HgSOa are quite soluble, providing potentially toxic levels of BaZ+and Hgz+, respectively. (4) The highly electronegative chlorine in ClOH "attracts" bonding electrons so that the CI-0 hond is strenethened. while the O-H bond is weakened. The \,pry 1 m electronegativity of sodium romparrd to coxygm weakens the N R - 0h n d so that OII readily "breaks Ihu~~."t:I) ,alThe i u m oI'tlw ruusses uf curnponmt neutnm, protons,and eb( trans is I ~ Lt Vr ~ the n atomic mass of an atom composed of neutrons, protons, and electrons. (b) For example, if we let A represent concentrated HzSO4 and B represent water, the result of adding A to B (carefully,with proper mixing) is much different (safer)than the result of adding B to A. (c) For example, (Mg HzSOd Ca(OH)?f Mg (H2SOd Ca(OH)z). (dl 1(mole NHd 1(mole HC1) = 1(moleNHnCI).(There are many other examples.) ~~~
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Detailed solutions available. Address your requests to Rod O'C
