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 $64g$ 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 × 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 × 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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