Question

What mass of ZnCO3 contains 3.11×1022 O atoms

Answer 1

The molecular formula of the compound is $ZnCO_{3}$, from the molecular formula it is clear that 1 mol of $ZnCO_{3}$ contains 3 mol of oxygen.

Also, in 1 mol there are $6.023\times 10^{23}$ atoms thus, 3 mol of oxygen will have $18.069\times 10^{23}$ atoms of oxygen.

Thus, there are $18.069\times 10^{23}$ atoms of oxygen present in 1 mol of $ZnCO_{3}$.

1 atom of oxygen will be there in $3\times 6.023\times 10^{23}=5.53\times 10^{-25}$ mol.

Number of oxygen atoms given is $3.11\times 10^{22}$ thus, this will be present in $3.11\times 10^{22}\times 5.53\times 10^{-25} mol.=0.01721 mol$ of $ZnCO_{3}$.

Molar mass of $ZnCO_{3}$ is 125.388 g/mol, thus, mass can be calculated as follows:

$n=\frac{m}{M}$

Rearranging the above equation,

$m=n\times M$

Putting the values,

$m=(0.01721 mol)\times (125.388 g/mol)=2.16 g$

Therefore, the mass of $ZnCO_{3}$  is 2.16 g.

Answer 2

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