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March 24, 2017

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a)The Young's modulus for a material is 5.0*10^10 N/m2. The material is stretched to a strain of 4.0*10^-3. How much elastic energy will be expended? (Express your answer in J/m3)

Knowing that the energy associated with the formation of 1 mole of vacancies in copper (Cu) is 104 kJ, determine the vacancy density (nv/cm3) in Cu at 1366 K. Assume the pre-exponential factor is one.


Can someone help me with those questions? I can help with the rest!!

  • Chemistry - ,

    Hi I am working on it. Meanwhile Can you help me with the 3th and 4th questions about the graphics?

  • Chemistry - ,

    3//1.13 ev
    semiconductor

    4//4th option
    n-type
    4th option
    intrinsic

  • Chemistry - ,

    Hi can you help me with first part of 1st question .
    answer of 2nd part is 189

  • Chemistry - ,

    can u help me with the formula of Cu bsc me temperature is 1056 plssssssssssssssssss help

  • Chemistry - ,

    Determine for solid manganese (Mn) the following:

    What is the atomic density (atoms/m) along the [110] direction of the Mn crystal?
    What are the number of nearest neighbors around an atom in the Mn crystal?
    Calculate the interplanar spacing (m) between {220} planes in the Mn crystal.

  • Chemistry - ,

    if someone help with those questions I'll post all the rest of answers

  • Chemistry - ,

    ΔHv=104,000J/6.02×10^23=1,7276*10^-19

    nv/Ns=e^{(-1.7276*10^-19)/[(1.381×10^−23)*(1366)]}=Result

    Use the result to substitute to:
    nv/Ns*ρ*Avogadro number/Mw(Cu)
    =
    nv/Ns(result from above) * 8.94*( 6.02*10^23/63.546)

  • Chemistry - ,

    watch out that the formula is negative (on e), so it should be in the range of x*10^-4 or 10^-5!
    And note, that I can not give you the right answer as I succeeded only on my third attempt :)
    I need help with 11 and 12.

  • Chemistry - ,

    1- 7.36e-2
    189
    2-metal
    Solid hydrogen has a half filled s-band
    insulator
    Solid helium has a filled s-band
    3-1.13
    semiconductor
    4-Ionization of phosphorus requires some minimum temperature
    n_type
    The concentration of conduction electrons is fixed by the concetration of phosphorus
    intrinsic
    5-2.44e9
    8
    1.025e-10
    6-1.8e-10
    7-BCC
    3.172
    1.37
    8- HELP !!!!!!!!!!!!!!!!!!!!!!!!!!
    9-(for energy 104 kj and vacancy density 1366 K) 8924699659276140118.9689358889623
    10-sample A
    sample B
    sample B
    sample D
    sample C
    sample C
    11-increase air flow on the bottom array
    12-2.773e-2
    13-2.58e16

  • Chemistry - ,

    The Young's modulus for a material is 8.0 x 1010 N/m2. The material is stretched to a strain of 9.0 x 10-3. How much elastic energy will be expended? (Express your answer in J/m3).

    Answer: 3240000

  • Chemistry - ,

    @Drew can you give me the formula?

  • Chemistry - ,

    Ev= elastic strain energy per unit vol=?

    Ev=(1/2)*Ey*E2(square)

    Ey= 8.0*10e+10 N/m2

    E= 9.0e-3 so square ->

    E2= 8.1e-5

  • Chemistry - ,

    thanks

  • Chemistry - ,

    Did you find the last quetion of homework 11?

  • Chemistry - ,

    No, I didn't find that answer.

  • Chemistry - ,

    can u help me with the formula of Cu bsc me temperature is 1056 plssssssssssssssssss help

  • Chemistry - ,

    nv/Ns=A*e(-Hv/(KT))

    K=1.381E-23
    Hv= 104000/6.023e+23
    A=1

    vacancy density=(nv/Ns)*Cu density*(6.023e+23/Cu atomic weight)

  • Chemistry - ,

    thnks @ Drew :)

  • Chemistry - ,

    Thanks Anon and Drew for the formula, I have other exams to prepare for so this was a life saver, I appreciate it truly. I however do not know how to calculate my result using exponents so can someone please solve for T=1373 K? I would be forever grateful. If I find the answers for the last few questions I will be sure to share it.

  • Chemistry - ,

    oops I reset it, new value of T is 1091 K somebody help please :'(

  • Chemistry - ,

    Never mind guys, alphawolfram did it for me :)~ any luck with the last three questions? Today is the deadline!

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