Question

If 16 g of oxygen contains 1 mole of oxygen atoms, calculate the mass of one atom of oxygen.

Answer 1

Hint: We know that atomic number of oxygen is 8 and atomic weight of oxygen is 16g/mol which contain $6.02\times {{10}^{23}}$ atoms of oxygen.
Complete step-by-step answer:
Here, it is given that: 16 g of oxygen contains 1 mole of oxygen atoms. In simple terms we can say that: mass of 1 mole oxygen atom (W) = 16 g / mol.
And this weight is the sum of mass of electrons and protons present in the oxygen. And the mass of the molecule of oxygen (${{O}_{2}}$) is 32u, here ‘u’ is the Dalton or unified atomic mass unit. It is a unit of mass widely used in physics and chemistry.
And we know that number of particles or atoms in one mole oxygen (${{N}_{A}}$) = $6.02\times {{10}^{23}}$/ mol
So, mass of $6.02\times {{10}^{23}}$atoms = 16 g
Then the mass of one atom of oxygen = Mass of one mole oxygen / number of atoms in one mole oxygen
= $\dfrac{W}{{{N}_{A}}}$
$=\dfrac{16g/mol}{6.02\times {{10}^{23}}/mol}$
= $2.658\times {{10}^{-23}}g/atom$.
So, the answer is $2.658\times {{10}^{-23}}g$.

Note: One mole (not one molecule) of oxygen atoms would weigh 16 g, because an oxygen atom weighs 16u. Don’t get confused with units. And this method or relation between mass of atom, number of atoms and mass of one mole can solve any of this type of problem.