Q.
The density of copper is 9×103kgm−3 and its atomic mass is 63.5u . Each copper atom provides one free electron. Estimate the number of free electrons per cubic metre in copper.
The density of copper, ρ=9×103kgm−3=9×106gm−3
Avogadro number, NA=6.023×1023
Mass of 1 mole of the copper atom, M=63.5g
Thus, the number of free electrons per volume is n=MNAρ=63.56.023×1023×9×106=8.5×1028m−3