Final answer:
To determine the moles of P2O3 required to react with 108 g H2O, we calculate the moles of H2O and then use the stoichiometry of the balanced chemical equation. We find that 2 moles of P2O3 are needed.
Step-by-step explanation:
To find out how many moles are present in 108 grams of water (H2O), we use the molecular weight of H2O which is 18.02 g/mol as given.
Using the formula:
Number of moles = mass (g) / molecular weight (g/mol),
we get the moles of H2O: 108 g / 18.02 g/mol.
We find that there are 6 moles of H2O. Now, looking at the balanced chemical equation P2O3 + 3H2O → 2H3PO3, we see that 3 moles of water react with 1 mole of P2O3. Therefore, to react with 6 moles of H2O, we would need 2 moles of P2O3.