- Which of the following is NOT a characteristic of an amphoteric species? A. Amphoteric species can act as an acid or a base, depending on its environment. B. Amphoteric species can act as an oxidizing or reducing agent, depending on its environment. C. Amphoteric species are sometimes amphiprotic. D. Amphoteric species are always nonpolar.
The Correct Answer and Explanation is :
Correct Answer: D. Amphoteric species are always nonpolar.
Explanation:
An amphoteric species is a substance that can act as both an acid and a base, depending on its chemical environment. This property makes them important in many chemical reactions, including biological and industrial processes. Let’s analyze each option to determine why D is the correct answer.
A. Amphoteric species can act as an acid or a base, depending on its environment. ✅ (True)
By definition, an amphoteric substance can donate protons (acting as an acid) or accept protons (acting as a base), depending on the surrounding conditions. A classic example is water (H₂O), which can donate a proton to become OH⁻ (hydroxide ion, acting as a base) or accept a proton to become H₃O⁺ (hydronium ion, acting as an acid).
B. Amphoteric species can act as an oxidizing or reducing agent, depending on its environment. ✅ (True)
Some amphoteric substances, such as zinc oxide (ZnO) and aluminum oxide (Al₂O₃), can act as either oxidizing or reducing agents. They react with both acids and bases, showcasing their dual nature. This characteristic is especially important in metallurgy and corrosion chemistry.
C. Amphoteric species are sometimes amphiprotic. ✅ (True)
An amphiprotic species is a specific type of amphoteric species that can donate or accept protons (H⁺). For example, HCO₃⁻ (bicarbonate ion) can act as an acid by donating H⁺ to form CO₃²⁻ or as a base by accepting H⁺ to form H₂CO₃. Since not all amphoteric species are necessarily amphiprotic, the word “sometimes” makes this statement true.
D. Amphoteric species are always nonpolar. ❌ (False)
Amphoteric species can be polar or nonpolar, depending on their molecular structure. Many amphoteric substances, like water (H₂O), amino acids, and bicarbonate (HCO₃⁻), are highly polar due to their ability to form hydrogen bonds or ionic interactions. Therefore, it is incorrect to say that all amphoteric species are nonpolar.
Thus, D is the correct answer because amphoteric species can be either polar or nonpolar, contradicting the statement.