Question

5x10-6 mol Na2C2O4 bileşiğinde kaç tane O atomu vardır?

Answer 1

There are 1.204 x 10¹⁹ atoms O

Further explanation  

The empirical formula is the smallest comparison of atoms of compound forming elements.  

A molecular formula is a formula that shows the number of atomic elements that make up a compound.  

1 mol of molecule Na₂C₂O₄ :

There are 4 mol of O in 1 mol of molecule Na₂C₂O₄

So for 5 x 10⁻⁶ mol Na₂C₂O₄ :

$\tt mol~O=4\times 5.10^{-6}=2.10^{-5}$

1 mole = 6.02.10²³ particles , so number of atoms O :

$\tt 2\times 10^{-5}\times 6.02\times 10^{23}=1.204\times 10^{19}$