I'm trying to solve this question:
We have a molecule composed of $3$ iron atoms, and $4$ atoms of another element. We are given the following information: it has $\pu{2.36 g}$ of iron for $\pu{3.26 g}$ of molecule.
I want to find the molar mass of the compound, I have tried so far: $$ m = \pu{3.26 g} = \pu{0.00326 kg}$$ Since it has $3$ atoms of $\ce{Fe}$ and $4$ atoms of an unknown substance, therefore: $$3 + 4 = 7~\text{atoms},\\ \pu{1 mol} = \pu{6.022* 10^23 atoms}\\ \frac{7}{\pu{6.022* 10^23}} = \pu{1.16 * 10^-23}$$
As we know: $M = m / n,$ I tried to divide $0.00326$ by $\pu{1.16 * 10^-23}$ and I obtained $\pu{2.79429 * 10^19}$, but the correct answer is $\pu{231.43 g/mol}$.
What I have done wrong?