Question

Hydrogen selenide (H2Se) reacts with water according to the following equation.

H2Se + H2O → SeH– + H3O+

In three to five sentences, identify the acid, base, conjugate acid, and conjugate base in this reaction. Use patterns in the periodic table to explain why the substances you identified acted as the acid and the base in this reaction.

Answer 1

In this reaction, H2Se acts as the acid and H2O acts as the base. The conjugate acid is SeH- and the conjugate base is H3O+.

H2Se acts as the acid because it donates a proton (H+) to H2O, forming the conjugate base SeH-. H2O acts as the base because it accepts the proton, forming the conjugate acid H3O+.

In the periodic table, elements in Group 16 (also known as Group VIA) tend to act as acids by donating protons. Hydrogen selenide (H2Se) is a covalent compound that belongs to Group 16, so it can readily donate a proton in this reaction. On the other hand, water (H2O) tends to act as a base because oxygen (O) is more electronegative than selenium (Se), making it a better proton acceptor.