1. PF Contest - Win "Conquering the Physics GRE" book! Click Here to Enter
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Calculating number of atoms in an alloy

  1. Sep 16, 2012 #1
    1. The problem statement, all variables and given/known data

    Germanium forms a substitutional solid solution with silicon. Compute the number of germanium atoms per cubic centimeter for a germanium-silicon alloy that contains 15 wt% Ge and 85 wt% Si. The densities of pure germanium and silicon are 5.32 and 2.33 g/cm3, respectively.

    2. Relevant equations

    I'm not sure on these. I will put the ones I think are applicable.

    C'1=(C1 A2)/((C1 A2)+(C2 A1))

    p (avg) = ((C'1 A1)+(C'2 A2))/((C'1 A1/p1)+(C'2 A2/p2))

    C = weight percent = wt%
    C' = atomic percent
    p = density
    A = atomic weight

    3. The attempt at a solution

    I can put the numbers in to get the atomic percents and the density of the alloy. I calculated 6.389 atomic% Ge and 93.611 atomic% Si. For the density of the alloy, I got 2.5445 g/cm3. The only problem is that I don't know how to get the number of Ge atoms in one cubic centimeter. How do I get there from where I am?
  2. jcsd
  3. Sep 20, 2012 #2
    No. of atoms of Ge
    =(2.5445/72.64)(6.02x10^23)= 2.11x10^22
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook