Question

2PH3  + 4O2 🡪  P2O5  +  3H2O

1. How many grams of O2 will completely react with 49.0 g PH3?

Answer 1

M(PH₃) = 34.00 g/mol

n(PH₃) $= \frac{49.0}{34.0} = 1.44 \;mol$

According to the reaction equation

n(O₂) = 2n(PH₃) $= 2 \times 1.44 = 2.88 \;mol$

M(O₂) = 32.00 g/mol

m(O₂) $= 2.88 \times 32 = 92.23 \;g$

Answer: 92.23 g