Question

Given the equation representing a reaction at equilibrium: if an acid is defined as an h+ donor, what is the acid in the forward reaction? oh– (aq) h2o(ℓ) nh3(g) nh4+(aq)

Answer 1

Answer:

Explanation:

According to Arrhenius Acid-Base Theory, acids are those substances that dissolved in water divide generating H⁺ together with an anion (ion with negative charge). In an aqueous solution, H⁺ protons immediately react with water molecules to form H₃O⁺ hydronium ions. A base, on the contrary, according to this theory, is a substance that liberates OH⁻ ions in aqueous solution.

This theory is valid only in aqueous medium.

You know: NH₃(g) + H₂O(l) → NH₄⁺(aq) + OH⁻(aq)

In this case, the water dissociates with the formation of hydrogen ions, H⁺, which NH₃ accepts to form the NH₄⁺ ion. So the water acts as an acid.

On the other hand, in reaction:

NH₄⁺(aq) + OH⁻(aq) → NH₃(g) + H₂O(l)

NH₄⁺ dissociates with the formation of hydrogen ions, H⁺, which water accepts to form the H₃O⁺ ion. So NH₄⁺ acts as an acid.

Answer 2

For reaction: NH₃(g) + H₂O(l) → NH₄⁺(aq) + OH⁻(aq), water (H₂O) is donor of proton (H⁺) and ammonia (NH₃) is acceptor of proton (base).
For reaction: NH₄⁺(aq) + OH⁻(aq) → NH₃(g) + H₂O(l) , NH₄⁺ is acid (donor of proton (H⁺)) and hydroxy anion (OH⁻) is base (acceptor of proton).
According to  Bronsted-Lowry theory acid are donor of protons and bases are acceptors of protons (the hydrogen cation or H⁺).