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Charge on 1 g N3- ion

  1. Apr 13, 2013 #1
    1. The problem statement, all variables and given/known data
    What is the charge in coulomb on 1 gram of N3- ions

    2. The attempt at a solution
    the atomic mass of nitrogen is 14 gram.
    hence 14 g nitrogen will contain 6.022*10^23 ions.
    therefore 1 g nitrogen will contain n=6.022*10^23/14 no. of ions.
    one N3- ion has a charge of q=4.8*10^-19 C.
    so n ions of N3- will carry a charge of n*q C= 2.065*10^4 C
    But this answer is wrong. Where am I going wrong?
    Does 14 g nitrogen contain Avogadro's no. of atoms?
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Apr 13, 2013 #2

    Curious3141

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    Homework Helper

    The atomic mass of N is 14Da (it is NOT 14g!). But the molecular mass of N3- is 14*3 = 42Da.

    Another mistake: the charge on one N3- ion is just e (a single electron charge).

    Hence your answer overestimates by a factor of 9.
     
    Last edited: Apr 13, 2013
  4. Apr 13, 2013 #3

    Borek

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    Staff: Mentor

    Lousy typing gives lousy results. N3- and N3- are different things.
     
  5. Apr 13, 2013 #4

    Curious3141

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    Very good point. He has to clarify if he meant nitride or azide (I assumed the latter).
     
  6. May 7, 2017 #5
    Your solution is right but the question you ask for might be for 1 g-ion.
    • 1 g-ion = (weight in grams of sum of atomic weight of atoms making the ion.)
    • Here N^3- has 14 amu so 1g-ion 14 gm.
    • So here we have to find for 14g that is 1mole of nitride ion.
    1 ion of nitride has =1.6 ×10^-19 × 3 C
    Therefore 6.022 × 10^23 ions has = 6.022 × 10^23 ×1.6 ×10^-19 × 3 C = 2.89 × 10^5 C.
     
    Last edited: May 7, 2017
  7. May 7, 2017 #6

    Borek

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    Staff: Mentor

    Welcome to the PF @Strawberry1711 - just in case, please read the forum rules.

    Stating that Coulomb equals Ampere definitely doesn't help. These are two different units.
     
  8. May 7, 2017 #7
    Sorry
    @Borek
    It's 2.89 × 10^5 C.
    And Thank you for telling me that I have corrected it.
     
    Last edited: May 7, 2017
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