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Homework Help: How do you find the number of electrons given a mass fo the object?

  1. Jan 14, 2013 #1
    1. The problem statement, all variables and given/known data

    (a) Calculate the number of electrons in a small, electrically neutral silver pin that has a mass of 13.0 g. Silver has 47 electrons per atom, and its molar mass is 107.87 g/mole.

    2. Relevant equations

    3. The attempt at a solution

    I thought to try using the molar mass given and dividing it by mass of the pin.
    107.87g/mole / 13 g = 8.298 1/mole

    After this point I didn't know what to do next
  2. jcsd
  3. Jan 14, 2013 #2
    How many atoms are in a mole?
  4. Jan 14, 2013 #3


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    Staff Emeritus
    Science Advisor
    Homework Helper

    I think you were trying to find the number of moles of silver in the pin, but you would up with a unit of 1/moles in your calculation.

    What does this tell you about how to do the calculation correctly?
  5. Jan 15, 2013 #4
    Thanks a lot! I used avogadro's number.

    (13g)/(107.87g/mole)*(6.022E23atoms/mole)*(47electrons) = 3.41E24 electrons in the silver pin
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