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Ammonia dissolved in water gives NH4+ and OH- ions. How is ammonia classified, and why?
AA strong base, since it reacts completely
BA strong acid, since it releases hydrogen ions
CA weak base, since it reacts only partially
DA weak acid, since it accepts hydrogen ions
Answer & Solution
Correct answer: C. A weak base, since it reacts only partially
1. Ammonia is not an ionic hydroxide, so it must react with water to make OH-.
2. In that reaction H+ moves from a water molecule to the NH3 molecule.
3. Since hydroxide is produced, ammonia is a base.
4. Only about 1% of the dissolved ammonia is present as NH4+, so the reaction is partial.
5. A partial reaction of this kind is what defines a weak base.
_Source: OpenStax Chemistry (CC BY 4.0), Ch 4 "Stoichiometry of Chemical Reactions", section 4.2 Classifying Chemical Reactions_
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