How many moles of phosphoric acid reacted?

Question

3Hg(OH)2+2H3(PO4)→Hg3(PO4)+6H2O

How many mol of phosphoric acid (H₃(PO₄)) reacted to form 3.13 x 10¹ mol of water (H₂O)?

Answer 1

Use dimensional analysis to answer this type of question:

3Hg(OH)₂ + 2H₃PO₄ ==> Hg₃PO₄ + 6H₂O

3.13x10¹ mol H2O x 2 mol H₃PO₄ / 6 mol H₂O = 1.04x10¹ moles H₃PO₄ = 10.4 moles H₃PO₄