[melindaa]

Hello,
I'm trying to write a molecular equation for a chemical reaction at its 3 equivalence points. Could somebody please check that I'm on the right track? Thank you 

A.   NaOH + H3PO4 → NaOH2+ + H2PO4-
B.   NaOH2+ + H2PO4- → NaOH3+2 + HPO4-2
C.   NaOH3+2 + HPO4-2 → NaOH4+3 + PO4-3

[Borek]

No, there is no such thing as NaOH₂⁺ (and subsequent sodium compounds).

What are products in the case of a simple reaction, like NaOH+HCl? Write them.

Or even better, try to think about NaOH as being completely dissociated. Which of the two ions produced during the dissociation will react?

[Arkcon]

Adding to what Borek: said, you have a reaction with 3 equivalence points, so if you were to plot the reaction, you'd see 3 separate plateaus.  Yet, you think there's only one reaction (like Borek: said, you made up products that don't exist in order to do that.)  Try to see what happens considering what you should observe.

[Arkcon]

Re-reading more carefully, I see you do have 3 reactions for the three equivalence points.  Still, like Borek said not  real ones.

[melindaa]

What are products in the case of a simple reaction, like NaOH+HCl? Write them.

Or even better, try to think about NaOH as being completely dissociated. Which of the two ions produced during the dissociation will react?

That was helpful. thanks. Here's my second attempt. I don't need to put charges because it's at equilibrium... right..??

A.   H3PO4 + NaOH → NaH2PO4 + H2O
B.   NaH2PO4 + NaOH → Na2HPO4 + H2O
C.   Na2HPO4 + NaOH → Na3PO4 + H2O

[Borek]

I don't need to put charges because it's at equilibrium...

No idea what you are trying to say here.

You can write these reaction equations as overall (which is what you did) or as net ionic. The latter makes more sense, but neither is related to the equilibrium.