Based on their molecular structure, choose the stronger acid from each pair of binary acids, and explain your choice: a. HF and HCl b. H2O and HF c. H2Se and H2S.

Name: Chemistry: A Molecular Approach
Author: Tro
ISBN: 9780134112831

검증된 단계별 안내

Identify the periodic trend for acidity in binary acids: Acidity generally increases down a group in the periodic table due to the increase in atomic size, which weakens the H-X bond, making it easier to donate a proton.

For pair (a) HF and HCl: Compare the position of fluorine and chlorine in the periodic table. Chlorine is below fluorine, indicating that HCl is a stronger acid than HF due to the weaker H-Cl bond.

For pair (b) H2O and HF: Consider the electronegativity of the central atom. Fluorine is more electronegative than oxygen, which makes HF a stronger acid than H2O because the H-F bond is more polar, facilitating proton donation.

For pair (c) H2Se and H2S: Compare the position of selenium and sulfur in the periodic table. Selenium is below sulfur, suggesting that H2Se is a stronger acid than H2S due to the larger atomic size of selenium, which weakens the H-Se bond.

Summarize the findings: In each pair, the stronger acid is determined by either the position in the periodic table (for pairs a and c) or the electronegativity of the central atom (for pair b).

주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Binary Acids

Binary acids are acids that consist of only two elements, typically hydrogen and a nonmetal. The strength of binary acids is influenced by the bond strength between hydrogen and the nonmetal; weaker bonds lead to stronger acids. For example, in the case of HF and HCl, the H-F bond is stronger than the H-Cl bond, making HF a weaker acid than HCl despite fluorine's high electronegativity.

Electronegativity

Electronegativity is the tendency of an atom to attract electrons in a chemical bond. In binary acids, the electronegativity of the nonmetal affects the acid's strength; higher electronegativity typically leads to stronger acids due to the greater polarity of the H-X bond. For instance, in comparing HF and HCl, while HF has a highly electronegative fluorine, the bond strength ultimately results in HCl being the stronger acid.

Bond Strength and Acid Strength

The strength of the bond between hydrogen and the nonmetal in a binary acid directly impacts the acid's strength. Weaker bonds are more easily broken, allowing the acid to donate protons (H+) more readily. For example, in the pair H2Se and H2S, the H-Se bond is weaker than the H-S bond, making H2Se the stronger acid because it can more easily release a proton.