Here's how to balance the chemical equation for the reaction of phosphoric acid (H₃PO₄) and calcium hydroxide (Ca(OH)₂) to form solid calcium phosphate (Ca₃(PO₄)₂) and water (H₂O):

1. Write the unbalanced equation:

H₃PO₄ (aq) + Ca(OH)₂ (aq) → Ca₃(PO₄)₂ (s) + H₂O (l)

2. Balance the calcium (Ca) atoms:

There's one calcium atom on the left and three on the right. Put a coefficient of 3 in front of Ca(OH)₂:

H₃PO₄ (aq) + 3Ca(OH)₂ (aq) → Ca₃(PO₄)₂ (s) + H₂O (l)

3. Balance the phosphate (PO₄) groups:

There's one phosphate group on the left and two on the right. Put a coefficient of 2 in front of H₃PO₄:

2H₃PO₄ (aq) + 3Ca(OH)₂ (aq) → Ca₃(PO₄)₂ (s) + H₂O (l)

4. Balance the hydrogen (H) atoms:

There are 12 hydrogen atoms on the left (6 from 2H₃PO₄ and 6 from 3Ca(OH)₂) and only 2 on the right. Put a coefficient of 6 in front of H₂O:

2H₃PO₄ (aq) + 3Ca(OH)₂ (aq) → Ca₃(PO₄)₂ (s) + 6H₂O (l)

5. Verify that the oxygen (O) atoms are balanced:

There are 14 oxygen atoms on both sides of the equation.

The balanced equation is:

2H₃PO₄ (aq) + 3Ca(OH)₂ (aq) → Ca₃(PO₄)₂ (s) + 6H₂O (l)