# Dissociation of H3PO4 and colligative properties

Which of the following solutions that have concentrations of $0.01\ \mathrm{M}$ show the highest elevation in boiling point and why?

A) $\ce{NaCl}$
B) $\ce{CaCl2}$
C) $\ce{H3PO4 }$
D) $\ce{C6H12O6}$ (glucose)

When dissolved in water, $\ce{H3PO4 }$ dissociates into 4 ions, which is more than any of the other compounds. Someone told me though, that because it's a weak-acid, it doesn't matter how many ions it has, and that $\ce{CaCl2}$ will still have the highest elevation boiling point. Is this true?

• Phosphoric acid won’t dissociate further than $\ce{H3O+ + H2PO4-}$ in a standard aquaeous solution. That’s only two ions. – Jan May 6 '16 at 22:06
• @Jan I've asked the same question on Quora(it wasn't active, that's why i asked it here). and this is what a chemist says : quora.com/… – James Sandler May 6 '16 at 22:10
• That person has not the slightest of clues what he is talking about. – Jan May 6 '16 at 22:10
• @Jan Lol. Why thank you very much for answering so quickly! – James Sandler May 6 '16 at 22:16
• If you want, you can write up a self-answer. The preferred Stack Exchange way of showing that you found a solution to your problem ;) – Jan May 6 '16 at 23:49