# Chemistry

posted by Anon

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!!

1. koala

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

2. Anon

3//1.13 ev
semiconductor

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

3. chimi

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

4. Mx

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

5. Mx

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.

6. Anon

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

7. Nano

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(result from above) * 8.94*( 6.02*10^23/63.546)

8. Nano

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.

9. Anon

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

10. Drew

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).

11. Anon

@Drew can you give me the formula?

12. Drew

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

13. Anon

thanks

14. Anon

Did you find the last quetion of homework 11?

15. Drew

No, I didn't find that answer.

16. Mx

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

17. Drew

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)

18. Mx

thnks @ Drew :)

19. KS

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.

20. KS

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

21. KS

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

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