Question

What is the maximum amount in moles of P2O5 that can theoretically be made from 112 g of O2 and excess phosphorus?
Express your answer to three significant figures and include the appropriate units.

Answer 1

$P_4+5O_2\to2P_2O_5$

moles of $O_2=\frac{112}{32}mol$

5 moles of $O_2$ form 2 moles of $P_2O_5$

so $\frac{112}{32}moles$ will form $\frac{2}{5}\times\frac{112}{32}=\frac{7}{5}mol=1.4moles$ of $P_2O_5$