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 $6.4g ($take the atomic weight of copper to be $64\ g\ mol^{-1}.)$
✓
Answer
$64$ grams of copper have $1$ mole
$6.4$ grams of copper have $0.1$ mole
$1$ mole $=$ No atoms
$0.1$ mole $= ($no $\times 0.1)$ atoms
$= 6 \times 10^{23}\times 0.1$ atoms $= 6 \times 10^{22}$ atoms
$1$ atom contributes $1$ electron
$6 \times 10^{22}$ atoms contributes $6 \times 10^{22}$ electrons.
$6.4$ grams of copper have $0.1$ mole
$1$ mole $=$ No atoms
$0.1$ mole $= ($no $\times 0.1)$ atoms
$= 6 \times 10^{23}\times 0.1$ atoms $= 6 \times 10^{22}$ atoms
$1$ atom contributes $1$ electron
$6 \times 10^{22}$ atoms contributes $6 \times 10^{22}$ electrons.
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