Question

the empirical formula of a compound is NO2. it's molecular mass is 92g/mol. What is its molecular formula?

Answer 1

The molecular formula:
$N_x(O_2)_x$

$M_{N_x(O_2)_x}=x \times M_N + x \times 2 \times M_O \\ \\ m_N=14 \ \frac{g}{mol} \\ m_O=16 \ \frac{g}{mol} \\ M_{N_x(O_2)_x}=92 \ \frac{g}{mol} \\ \\ 92=x \times 14+x \times 2 \times 16 \\ 92=14x+32x \\ 92=46x \\ \frac{92}{46}=x \\ x=2 \\ \\ N_2(O_2)_2 \Rightarrow N_2O_4$

The molecular formula is N₂O₄.