Question

A sample of 3.62 moles of diphosphorous trioxide is

Answer 1

$H_3PO_3$$2H_3PO_3$$2H_3PO_3$$P_2O_3$Answer:

B

Explanation:

This question is about stoichiometry. From the balanced equation $P_2O_3 + 3H_2O$⇒$2H_3PO_3$, we see that 3 moles of water is needed to react with 1 mole of $P_2O_3$.

This means that, to fully react 3.62 moles of $P_2O_3$, we would need 3*3.62 or  10.86 moles of water. However, we only have 6.31 moles, so water is the limiting reactant.

Since 3 moles of water react with 1 mole of $P_2O_3$, 6.31 moles of water can fully react with 6.31÷3 or 2.1033 moles of $P_2O_3$.

From the balanced equation, we see that every mole of $P_2O_3$ reacted gets you 2 moles of $2H_3PO_3$. Therefore, 2.1033 moles of $P_2O_3$ would give you approximately 4.21 moles of $H_3PO_3$.