Question

Assume that each atom in a copper wire contributes one free electron. Estimate the number of free electrons in a copper wire having a mass of $6.4$g (take the atomic weight of copper to be $64$ g $mo{l}^{-1}$).

Answer 1

$64$ grams of copper have $1$ mole

So, $6.4$ grams of copper have $0.1$ mole
$1$ mole $=N_o$ atoms

Then, $0.1$ mole $=(no\times 0.1)$ atoms

So, number of atoms can be:

$n=6\times {10}^{23}\times 0.1$ atoms $=6\times {10}^{22}$ atoms

$1$ atom contributes $1$ electron

$6\times {10}^{22}$ atoms contributes $6\times {10}^{22}$ electrons.