balanced equation for the complete nuetralization of H3PO4 with Ca (OH)2

Just by looking at it, I'm guessing it's a double replacement. That's where the ions do a little dance and just switch up.

PO4 is 3- and H3 is 3+ --- Ca is 2+ and (OH)2 is 2-

The PO4 will team up with the Ca and the H will team up with the OH. The trick is to get the ions to match up and also the number of atoms needed.

H3PO4 + Ca(OH)2 = HOH + Ca3(PO4)2

The problem here is the beginning of the equation is not really equal to the end of the equation. You need to add numbers in the right places to get complete neutralization.

2H_3PO_4 + 3Ca(OH)_2 = 6HOH + Ca_3(PO_4)_2

Phosphoric acid has 3 acidic protons and you can think of them being replaced one by one. Infojunkie's answer is correct !

Great explanation. Thank you!