PT: \(4P+5O_2\underrightarrow{t^o}2P_2O_5\)
Ta có: \(n_P=\dfrac{24,8}{31}=0,8\left(mol\right)\)
\(n_{O_2}=\dfrac{40}{32}=1,25\left(mol\right)\)
Xét tỉ lệ: \(\dfrac{0,8}{4}< \dfrac{1,25}{5}\), ta được O2 dư.
Theo PT: \(n_{P_2O_5}=\dfrac{1}{2}n_P=0,4\left(mol\right)\)
\(\Rightarrow m_{P_2O_5}=0,4.142=56,8\left(g\right)\)