4) PCl5 + H2O → H3PO4 +HCl What is the ratio of H2O to H3PO4? How many moles of H3PO4 are produced when12 moles of H2O are fully reacted with PCl5?

Answer 1

The ratio comes from the coefficients of the balanced equation

1. Balance the equation: PCl₅ + H₂O -->H₃PO₄ + HCl
2. PCl₅ + 4H₂O -->H₃PO₄ + 5HCl
3. There is a ratio of 4 H₂O : 1 H₃PO₄
4. Use mole ratio to convert moles of H₂O to moles of H₃PO₄
5. 12 mol H₂O *(1 mol H₃PO₄ /4mol H₂O) = 3 mol H₃PO₄

Answer 2

The ratio of H2O and H3PO4 is 4 to 1; For example, we start from 1 mol of PCl5 and to equate the formula, we produce 5 mol of HCl and 1 mol of H3PO4 (1 P to 1 P and 5 Cl to 5 Cl), on the right side of formula, we have 1 H3PO4 and 5 HCl, totally 8 H, so there should be 4 H2O on the left side.

So 3 mols of H3PO4 will be produced when 12 mols of H2O are used.