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Chapter 4.9: End of Chapter Material

  • Page ID
    19897
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    Prince George's Community College
    General Chemistry for Engineering
    CHM 2000

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    Unit I: Atoms      Unit II: Molecules     Unit III: States of Matter     Unit IV: Reactions     Unit V: Kinetics & Equilibrium
    Unit VI: Thermo & Electrochemistry
         Unit VII: Nuclear Chemistry

    Application Problems

    Problems marked with a ♦ involve multiple concepts.

    1. Until recently, benzidine was used in forensic medicine to detect the presence of human blood: when mixed with human blood, benzidine turns a characteristic blue color. Because benzidine has recently been identified as a carcinogen, other indicators have replaced it. Draw the complete Lewis dot structure for benzidine.

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    2. There are three possible ways to connect carbon, nitrogen, and oxygen to form a monoanion: CNO, CON, and OCN. One is the cyanate ion, a common and stable species; one is the fulminate ion, salts of which are used as explosive detonators; and one is so unstable that it has never been isolated. Use Lewis electron structures and the concept of formal charge to determine which isomer is cyanate, which is the fulminate, and which is the least stable.

    3. The colorless gas N2O4 is a deadly poison that has been used as an oxidizing agent in rocket fuel. The compound has a single N–N bond, with a formal charge of +1 on each nitrogen atom. Draw resonance structures for this molecule.

    4. ♦ An atmospheric reservoir species is a molecule that is rather unreactive, but it contains elements that can be converted to reactive forms. For example, chlorine nitrate (ClONO2) is a reservoir species for both chlorine and nitrogen dioxide. In fact, most of the chlorine in the atmosphere is usually bound up in chlorine nitrate as a result of the reaction of ClO with NO2.

      1. Draw Lewis electron structures for each species in this reaction. What difficulty is associated with the structure of the reactants? How does this affect the reactivity of the compounds?

        Chlorine nitrate can react in a surface reaction with water to form HClO and nitric acid.

    Answers

    1. 185c3e0e4b207beaf65ba439659a311c.jpg

    2. 5502f72988e24019da127cc690defe19.jpg
      1. ClO + NO2 → ClONO2
      2. 7917434b5b7ce970bb3af5713c053838.jpg

        Both reactants have one unpaired electron, which makes them more reactive than might otherwise be expected.

      3. ClONO2 + H2O → HClO + HONO2

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    Contributors

    • Anonymous

    Modified by Joshua Halpern, Scott Sinex and Scott Johnson

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