Question

The net ionic equation, H3PO4 (aq) + 3 OH− (aq) Imported Asset PO4−3 (aq) + 3 H2O (l), best represents which type of acid-base reaction?
strong acid-strong base

weak acid-strong base

strong acid-weak base

weak acid-weak base

Answer 1

Answer:

Weak acid - strong base

Explanation:

H₃PO₄ → Phosphoric acid.

This is a weak that has three dissociations in order to give hydronium to the medium and to produce the phosphate anion. The equations are:

H₃PO₄  + H₂O  ⇄  H₃O⁺  +  H₂PO₄⁻               Ka1

H₂PO₄⁻  + H₂O  ⇄  H₃O⁺ +  HPO₄⁻²               Ka2

HPO₄⁻²  + H₂O  ⇄  H₃O⁺  +  PO₄⁻₃             Ka3

As the H₃PO₄ is a weak acid then the water behaves as a strong base.

If we follow the Brownsted Lory idea, water becomes a strong base cause it receives the H⁺ from water, then the H₃O⁺ becomes the conjugate weak acid.

Anions from the H₃PO₄,  diacid phosphate and monoacid phosphate assume the rol of the conjugate strong base, they all recieve proton but this is a special case, because both anions can recieve all release the proton. That's why, they also are amphoteric