Question

I have a 1cm3 cube shaped piece of gold (Au) at 900o C. The atomic weight Au is 196.9 g/mol and its density at 900o C is 18.63g/cm3 .

a) If the formation energy for vacancies are 0.98eV/atom, what is the number of vacancies in my piece of gold.

b) Gold expands upon heating and contracts upon cooling. If the thermal expansion coefficient which is defined as the change in length divided by the original length was 14 ppm/K (ppm means parts per million, 10-6 ) where the initial length is length at 0oC and the final length is length at 900o C, what is the number of vacancies in my cube at 0o C. Assume that the formation energy for vacancies is not a function of temperature.

Answer 1