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# Energy for vacancy formation in aluminium.?

(This is the last time I am doing a Uni course without purchasing the textbook! =S ).

Q. "Calculate the energy for vacancy formation in aluminium, given that the equilibrium number of vacancies at 500°C is 7.57x10^23 m^-3. The atomic weight and density (at 500°C) for aluminium are, respectively, 26.98 g/mol and 2.62 g/cm^3."

Now from that I gather this:

Nv = 7.57x10^23 m^-3

k = 1.38 x 10^-23 J/K (Boltzmann constant)

T = 500+273.15 = 773.15K

Am finding the energy for vacancy formation, Qv.

With this formula: Nv = N e^ (-Qv/kt)

I am wondering, I have TWO missing variables (Qv and N).

Can anyone do this question??

Much appreciated =).

Lachy.

### 1 Answer

- 1 decade agoFavorite Answer
haha.. studying for MATE1000 i see..

well, here's your answer!

To solve for N, use the following equation:

N = {(Avogadro's number)*Density} / Atomic weight

The solve from there using your formula.

Cheer, Good luck tomorrow