chem question help 21-3

Question

The following chemical equation has NOT been balanced.

 

H₃PO₄ + Ca(OH)₂ --> Ca₃(PO₄)₂ + H₂O

 

How many grams of calcium hydroxide are needed to produce 17.94 grams of water?

Answer value

Answer 1

Balancing was slightly tricky; I get 2 H₃PO₄ + 3 Ca(OH)₂ --> Ca₃(PO₄)₂ + 6 H₂O.

Then (17.94g H₂O) * (1 mol H₂O / 18.02g H₂O) * (3 mol Ca(OH)₂ / 6 mol H₂O) * (74.10g Ca(OH)₂ / 1 mol Ca(OH)₂ ) = 36.89g Ca(OH)₂ .