Question

For the balanced chemical reaction below:

P4O10 (g) + 6 H2O (l) → 4 H3PO4 (aq)

(a) Calculate the moles of water if there are 9.19 grams of tetraphosphorus decoxide.

(b) Calculate the grams of water if there are 0.730 moles of tetraphosphorus decoxide.

(c) Calculate the grams of tetraphosphorus decoxide if there are 5.41 grams of H3PO4.

(d) Calculate the moles of H3PO4 if there are 0.604 moles of tetraphosphorus decoxide.

I am really just unsure how to set up the formula.

Answer 1

a) molar mass of P₄O₁₀ = 283.889 gm/mol
    moles of P₄O₁₀ = 9.19 gms / 283.889 gm/mol = 0.032371 mol of P₄O₁₀
   moles of water = 6*0.032371 = 0.19423 mol of H₂O
b) mol of P₄O₁₀ = 0.730 mol
   moles of water = 6 * 0.730 = 4.38 moles of H₂O
   grams of water = 4.38 mol of H₂O * 18 gm/mol = 78.84 gm of H₂O
c) molar mass of H₃PO₄ = 98 gm/mol
   mol of H₃PO₄ = 5.41 gm / 98 gm/mol = 0.055204 mol
  moles of P₄O₁₀ required = (0.055204 mol / 4) *1 = 0.013801mol
  grams of P₄O₁₀ required = 0.013801mol * 283.889 gm/mol = 3.91795 gms of P₄O₁₀
d) moles of H₃PO₄ = 4*0.604 mol of P₄O₁₀ = 2.416 mol of H₃PO₄