Question

According to the Bronsted-Lowry theory, which of the following would you expect to act as an acid? Which as a base? Both acid and base? (a) \(\mathrm{CHO}_{2}^{-}\) (b) \(\mathrm{NH}_{4}^{+}\) (c) \(\mathrm{HSO}_{3}^{-}\)

Short answer

Question: Identify the Bronsted-Lowry acids, bases, and amphoteric species for the following chemical species: (a) CHO₂⁻, (b) NH₄⁺, (c) HSO₃⁻. Answer: (a) CHO₂⁻ acts as a base, (b) NH₄⁺ acts as an acid, and (c) HSO₃⁻ acts as both an acid and a base (amphoteric).

Step-by-step solution

Analyze the first chemical species: \(\mathrm{CHO}_{2}^{-}\)

Look for any potential protons that could be donated or identify the potential sites for a proton to be accepted. In the case of \(\mathrm{CHO}_{2}^{-}\), the oxygen atoms may accept a proton, and no protons can be donated. Thus, \(\mathrm{CHO}_{2}^{-}\) is a base since it can only accept a proton.

Analyze the second chemical species: \(\mathrm{NH}_{4}^{+}\)

Again, look for protons that can be donated or the potential sites for a proton to be accepted. \(\mathrm{NH}_{4}^{+}\) has 4 hydrogens, one of which can be donated and no available sites to accept a proton. Thus, \(\mathrm{NH}_{4}^{+}\) is an acid, since it can only donate a proton.

Analyze the third chemical species: \(\mathrm{HSO}_{3}^{-}\)

Examine the protons that can be donated and the potential sites for a proton to be accepted. \(\mathrm{HSO}_{3}^{-}\) has an acidic hydrogen (the one attached to the S) that can be donated and free oxygen atoms that can accept protons. As a result, \(\mathrm{HSO}_{3}^{-}\) is an amphoteric species because it can both donate and accept a proton. To summarize the results: (a) \(\mathrm{CHO}_{2}^{-}\) acts as a base. (b) \(\mathrm{NH}_{4}^{+}\) acts as an acid. (c) \(\mathrm{HSO}_{3}^{-}\) acts as both an acid and a base (amphoteric).