Find total ionic (balanced equation) for this particular reaction.

[name_ask17]

Homework Statement

Find the total ionic (balanced) equation of the reaction of calcium hydroxide and phosphoric acid in aqueous solution.

Homework Equations

Solubility rules

The Attempt at a Solution

First, I balanced the reaction.
3Ca(OH)2 + 2H3PO4 --> Ca3(PO4)2 + 6H2O
The part I'm stuck at is I don't know what to break up and what to leave. I know the solubility rules, but for some reason I keep getting this question wrong.

I know that Ca(OH)2 can break up into 3Ca2+ + 6OH-
But is that the only one that breaks up?
I looked it up and I'm getting mixed results. Please help me if you can. Thanks in advance.

 

[Borek]

No idea what the correct answer is, as unfortunately it depends on what the teacher had on mind

Calcium hydroxide is weakly soluble (so mostly present as a solid), but it is a strong base (so it is 100% dissociated).

Phosphoric acid is a weak acid, so in typical solution it will be dissociated only partially, and only the first proton will be dissociated in substantial amounts (for example in 1M solution about 8%), yet it can react all the way down to PO₄^3-.

Apparently you are expected to ignore some of these information and give answer based on some general (but not always correct) rules.

 

[name_ask17]

Thank you so much. I figured it out. They wanted me to look as phosphoric acid and calcium phosphate, both as insoluble. Thanks again!