Question

How many atoms of mercury are present in 1 g of mercury. ( Atomic mass of mercury = $200.6{\mathrm{gmol}}^{-1}$ )

Answer 1

Step 1:

Finding the moles of mercury:

Given mass of mercury = 1g

Atomic mass of mercury = $200.6{\mathrm{gmol}}^{-1}$

$$\begin{gathered} \mathrm{Number}\mathrm{of}\mathrm{moles}=\frac{\mathrm{Given}\mathrm{mass}}{\mathrm{Atomic}\mathrm{mass}} \\ \mathrm{Number}\mathrm{of}\mathrm{moles}\mathrm{of}\mathrm{mercury}=\frac{1}{200.6}=4.985\times {10}^{-3}\mathrm{moles} \end{gathered}$$

Hence, the number of moles of mercury is $4.985\times {10}^{-3}\mathrm{moles}$

Step 2:

Finding the number of atoms of mercury:

We know that,

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

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

$4.985\times {10}^{-3}\mathrm{moles}$ of mercury $=6.022\times {10}^{23}\times 4.985\times {10}^{-3}$

$=3.002\times {10}^{21}\mathrm{atoms}\mathrm{of}\mathrm{mercury}$

Hence, 1g of mercury contains $3.002\times {10}^{21}$ atoms of mercury.