Problem 93 - Chemistry The Central Science

Question

Indicate whether each of the following statements is true or false. For each statement that is false, correct the statement to make it true. (a) In general, the acidity of binary acids increases from left to right in a given row of the periodic table. (b) In a series of acids that have the same central atom, acid strength increases with the number of hydrogen atoms bonded to the central atom. (c) Hydrotelluric acid \(\left(\mathrm{H}_{2} \mathrm{Te}\right)\) is a stronger acid than \(\mathrm{H}_{2} \mathrm{~S}\) because Te is more electronegative than \(\mathrm{S}\).

Step-by-Step Solution

Answer

(a) True (b) False. Corrected statement: "In a series of acids that have the same central atom, acid strength may not solely depend on the number of hydrogen atoms bonded to the central atom but also on factors like electronegativity, size of the central atom and the stability of the resulting anion." (c) False. Corrected statement: "Hydrotelluric acid \(\left(\mathrm{H}_{2} \mathrm{Te}\right)\) is a stronger acid than \(\mathrm{H}_{2} \mathrm{S}\) because Te is larger in size than \(\mathrm{S}\), which results in longer and weaker bonds with hydrogen, making it easier to release \(\mathrm{H}^{+}\) ions."

Step 1: Statement (a) Analysis

In general, the acidity of binary acids increases from left to right in a given row of the periodic table. This is because the acidity of the binary acid is related to the strength of the bond between the hydrogen and the other element in the binary acid. As you go from left to right in a row of the periodic table, electronegativity increases, making the bond easier to break and forming \(\mathrm{H}^{+}\) ions, which leads to higher acidity. Therefore, statement (a) is true.

Step 2: Statement (b) Analysis

In a series of acids that have the same central atom, acid strength increases with the number of hydrogen atoms bonded to the central atom. This statement is not true in general, because the acidity depends on the dissociation of hydrogen from the acid to produce \(\mathrm{H}^{+}\) ions. The number of hydrogens bonded to the central atom does not directly determine how easily those hydrogen atoms are released, and therefore it does not directly determine the acidity. Corrected statement (b): "In a series of acids that have the same central atom, acid strength may not solely depend on the number of hydrogen atoms bonded to the central atom but also on factors like electronegativity, size of the central atom and the stability of the resulting anion."

Step 3: Statement (c) Analysis

Hydrotelluric acid \(\left(\mathrm{H}_{2} \mathrm{Te}\right)\) is a stronger acid than \(\mathrm{H}_{2} \mathrm{S}\) because Te is more electronegative than \(\mathrm{S}\). This statement is false because it is based on the wrong reason. Although Te is less electronegative than S, it is a larger sized atom, making the bond longer and easier to break, resulting in the release of more \(\mathrm{H}^{+}\) ions and a stronger acid. Corrected statement (c): "Hydrotelluric acid \(\left(\mathrm{H}_{2} \mathrm{Te}\right)\) is a stronger acid than \(\mathrm{H}_{2} \mathrm{S}\) because Te is larger in size than \(\mathrm{S}\), which results in longer and weaker bonds with hydrogen, making it easier to release \(\mathrm{H}^{+}\) ions." Final answers: (a) True (b) False, corrected statement provided. (c) False, corrected statement provided.