[Highschool - Chemistry] Chemical Reactions and Equations

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  • chez-the-guy
    FFR Player
    • Apr 2012
    • 348
    #1

    [Highschool - Chemistry] Chemical Reactions and Equations

    So for one of my summer assignments that I have to do to take AP Chemistry next year, I have to answer a couple of questions.
    I've stumbled on some:



    I have all four parts of #6 balanced and I know the reaction types.

    However, #7 refers back to the fourth equation of #6 and asks for the net ionic equation of:

    Pb(NO3)2 + 2NaCL -> PbCl2 + 2NaNO3
    (I might have balanced this incorrectly)

    However, I don't understand what an ionic equation should be / how to find it (much less a net ionic equation).

    Also in number 8 it asks for the substance being oxidized and reduced for the first equation in #6:

    Br2 + 2NaI -> I2 + 2NaBr

    So if, by definition, the substance being oxidant gains electrons (and is reduced) in a chemical reaction, does that mean that bromine is the substance being oxidized (because of it gaining an electron from Br2 to Br on the reactants side)?
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    • ___________
      Banned
      • Sep 2012
      • 585
      #2
      Re: [Highschool - Chemistry] Chemical Reactions and Equations

      When an ionic compound such as NaCl goes into water, it dissociates into Na+ and Cl- ions. So does Pb(NO3)2, dissociating into Pb(2+) and NO3- ions. So an ionic equation would be writing out problem 6d, only with ions instead of the compounds.

      It is a good rule of thumb to memorize that alkaline ions and nitrates are ALWAYS soluble in water. Other ions may or may not precipitate depending on the other ion.

      So, when you write out the ionic equation, you notice that some of the ions remain unchanged. These are called the spectator ions of the reaction. When you exclude these spectator ions, you get a net ionic equation. Hopefully that helps~

      Also: in the redox reaction, bromine gains electrons; it's the species that's being reduced. You had it the other way around.

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        • chez-the-guy
          FFR Player
          • Apr 2012
          • 348
          #3
          Re: [Highschool - Chemistry] Chemical Reactions and Equations

          Okay! I get both, thanks :3

          Also, when writing the ionic equation, is it mandatory to write the charges on each of the ion as well?

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            • ___________
              Banned
              • Sep 2012
              • 585
              #4
              Re: [Highschool - Chemistry] Chemical Reactions and Equations

              Yes.

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