Use the periodic table to complete the activity. An illustration shows the periodic table of elements with elements arranged in increasing order of atomic number in 18 columns (groups) and 7 rows (periods). The electronegativity of elements increases from left to right, across a period. The hydrogen on the left is included in group with medium electronegativity. Also, fluorine is shown as element with highest electronegativity. 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 the periodic table to explain why each substance acted as the acid or the base in this reaction.

Question

Use the periodic table to complete the activity.  An illustration shows the periodic table of elements with elements arranged in increasing order of atomic number in 18 columns (groups) and 7 rows (periods). The electronegativity of elements increases from left to right, across a period. The hydrogen on the left is included in group with medium electronegativity. Also, fluorine is shown as element with highest electronegativity.  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 the periodic table to explain why each substance acted as the acid or the base in this reaction.

GPT-4o mini · Answer

In the reaction $ \text{H}_2\text{Se} + \text{H}_2\text{O} \rightarrow \text{SeH}^- + \text{H}_3\text{O}^+ $, hydrogen selenide ($ \text{H}_2\text{Se} $) acts as the acid, while water ($ \text{H}_2\text{O} $) serves as the base. The conjugate acid formed is the hydronium ion ($ \text{H}_3\text{O}^+ $), and the conjugate base produced is the selenide ion ($ \text{SeH}^- $). Hydrogen selenide donates a proton (H⁺) to water, demonstrating its acidic behavior, attributed to the relatively low electronegativity of selenium compared to oxygen. This results in the formation of the conjugate base $ \text{SeH}^- $ which retains the negative charge after losing a proton. Water, with its higher electronegativity, effectively accepts a proton, making it act as the base and resulting in the formation of the conjugate acid $ \text{H}_3\text{O}^+ $.