Question 1

How are Arrhenius and Brønsted-Lowry acids different?

Accepted Answer

An Arrhenius acid produces hydronium ions in water, while a Brønsted-Lowry acid is defined more broadly as any proton donor. The latter definition also applies to reactions that are not framed as aqueous ionisation.

Question 2

Why is water shown as H₃O⁺ instead of a free H⁺ ion?

Accepted Answer

In the aqueous model, a transferred proton attaches to a water molecule and forms hydronium, H₃O⁺. This gives a more realistic representation of the species present in the water cluster than a free, unsupported H⁺ sphere.

Question 3

What are the conjugate pairs in the HCl reaction?

Accepted Answer

The conjugate pairs are HCl/Cl⁻ and H₃O⁺/H₂O. HCl donates H⁺ and becomes Cl⁻, while H₂O accepts H⁺ and becomes H₃O⁺.

Question 4

Does water act as both an acid and a base in the ammonia reaction?

Accepted Answer

Not in the displayed reaction. H₂O donates a proton and acts as the acid, while NH₃ accepts it and acts as the base. Water is amphoteric overall because it can donate or accept protons in different reactions.

Question 5

Why is the NH₃–BF₃ bond a Lewis coordinate bond?

Accepted Answer

Nitrogen donates its lone pair into the vacant p orbital of electron-deficient boron in BF₃. The resulting N→B bond contains two electrons, and both come from nitrogen; this reaction does not require proton transfer.

Proton Relay — Arrhenius, Brønsted & Lewis in One 3D Water Cluster

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