How many molecules are in 12.8 g n2o4

To calculate number of molecules, we first need to calculate the number of moles of N₂O₄.

Number of moles of N₂O₄ = \frac{Given mass}{Molar mass of N₂O₄}

Molar mass of N₂O₄= 92 g/mol

Given mass of N₂O₄= 12.8 g

Number of moles of N₂O₄=\frac{Given mass}{Molar mass of methane}

=\frac{12.8}{92}

= 0.139 mol

Number of molecules of N₂O₄ = 0.139\times 6.023 \times 10^{23}

= 8.37 × e²²

alchemy hadn't scientific methods of study, appeal to mysticism and fantasy, the knowledge of chemistry and physics were modest at that time.

alchemy was - but as new rules were discovered it either changed into chemistry or it became "unscientific".