Neutralization Reaction (Textbook Exercise J.9B)

[Sasha Gladkikh 2A]

Textbook Exercise J.9 states:

"Identify the salt that is produced from the acid–base neutralization reaction between (a) potassium hydroxide and acetic acid, CH₃COOH; (b) ammonia and phosphoric acid; (c) calcium hydroxide and bromous acid; (d) sodium hydroxide and hydrosulfuric acid, H₂S (both H atoms react). Write the complete ionic equation for each reaction."

For part B, the answer is:

3NH_3(aq) + 3H⁺ + PO₄^3-_(aq) → 3NH₄⁺_(aq) + PO₄^3-_(aq)

The acid and base involved in this neutralization reaction are H₃PO₄ and NH₃, which are both weak. In the answer key, why does the weak acid H₃PO₄ dissociate? In the textbook, it states that when writing the neutralization of a weak acid or a weak base, the formula for the molecular form of the weak acid or base is used, because intact acid molecules are the dominant species in solution.

Also, why is H₂O_(l) not included in the complete ionic equation?

[Jonathan Sautter 1J]

The reason for this is that acids donate protons while bases accept protons. Due to this, NH3 is going to accept the 3 H+ ions from PO4 and create (NH4)3PO4. The reason that water is not formed in this reaction is because water is only formed in a neutralization reaction when a strong base is present. If the base is not strong, then water will not be created.