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October 21, 2014

October 21, 2014

Posted by **Anon** on Friday, November 15, 2013 at 2:28pm.

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 -
**koala**, Friday, November 15, 2013 at 2:58pmHi I am working on it. Meanwhile Can you help me with the 3th and 4th questions about the graphics?

- Chemistry -
**Anon**, Friday, November 15, 2013 at 3:32pm3//1.13 ev

semiconductor

4//4th option

n-type

4th option

intrinsic

- Chemistry -
**chimi**, Saturday, November 16, 2013 at 12:39amHi can you help me with first part of 1st question .

answer of 2nd part is 189

- Chemistry -
**Mx**, Saturday, November 16, 2013 at 1:59amcan u help me with the formula of Cu bsc me temperature is 1056 plssssssssssssssssss help

- Chemistry -
**Mx**, Saturday, November 16, 2013 at 2:01amDetermine 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 -
**Anon**, Saturday, November 16, 2013 at 4:48amif someone help with those questions I'll post all the rest of answers

- Chemistry -
**Nano**, Saturday, November 16, 2013 at 5:47amΔHv=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 -
**Nano**, Saturday, November 16, 2013 at 5:52amwatch 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 -
**Anon**, Saturday, November 16, 2013 at 8:07am1- 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 -
**Drew**, Saturday, November 16, 2013 at 8:42amThe 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 -
**Anon**, Saturday, November 16, 2013 at 8:53am@Drew can you give me the formula?

- Chemistry -
**Drew**, Saturday, November 16, 2013 at 9:11amEv= 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 -
**Anon**, Saturday, November 16, 2013 at 9:36amthanks

- Chemistry -
**Anon**, Saturday, November 16, 2013 at 9:38amDid you find the last quetion of homework 11?

- Chemistry -
**Drew**, Saturday, November 16, 2013 at 9:54amNo, I didn't find that answer.

- Chemistry -
**Mx**, Saturday, November 16, 2013 at 1:45pmcan u help me with the formula of Cu bsc me temperature is 1056 plssssssssssssssssss help

- Chemistry -
**Drew**, Saturday, November 16, 2013 at 2:00pmnv/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 -
**Mx**, Saturday, November 16, 2013 at 2:02pmthnks @ Drew :)

- Chemistry -
**KS**, Saturday, November 16, 2013 at 3:55pmThanks 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 -
**KS**, Saturday, November 16, 2013 at 4:09pmoops I reset it, new value of T is 1091 K somebody help please :'(

- Chemistry -
**KS**, Sunday, November 17, 2013 at 7:54pmNever mind guys, alphawolfram did it for me :)~ any luck with the last three questions? Today is the deadline!

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