Question

Calculate the number of Iron atoms in a piece of Iron weighing $2.8\mathrm{g}$. (Atomic Mass Of Iron $=56\mathrm{g}$)

Answer 1

Step 1: Analyse given data

It is given in the question statement, that,

Weight of Iron ($\mathrm{Fe}$) $=2.8\mathrm{g}$

Atomic mass of Iron $=56\mathrm{g}$

Step 2: Find number of moles of Iron

The number of moles can be calculated as:

$\mathrm{Number}\mathrm{of}\mathrm{moles}=\frac{\text{Given weight}}{\text{atomic mass}}$

Moles of iron $=\frac{\text{wt. of iron}}{\text{atomic mass}}=\frac{2.8}{56}=0.05\mathrm{moles}$
Step 3: Find the number of Iron atoms

According to the Avogadro's law:

$1\mathrm{mole}=6.022\times {10}^{23}\mathrm{atoms}$

So. $0.05$ moles $=6.022\times 0.05\times {10}^{23}$ atoms $=3.0115\times {10}^{22}$ atoms
Thus, the number of Iron atoms in a piece of Iron weighing $2.8\mathrm{g}$ is $3.0115\times {10}^{22}$atoms