Identify the stronger acid in each of the following pairs. Explain your reasoning. (b) H3PO4 or H3AsO4

Verified step by step guidance

1. Identify the central atoms in each acid: H_3PO_4 has phosphorus (P) and H_3AsO_4 has arsenic (As).
2. Consider the position of these elements in the periodic table: Phosphorus is above arsenic in the same group.
3. Recall that acidity generally increases with the electronegativity of the central atom in oxoacids.
4. Phosphorus is more electronegative than arsenic, which suggests that H_3PO_4 is likely to be a stronger acid than H_3AsO_4.
5. Conclude that H_3PO_4 is the stronger acid due to the higher electronegativity of phosphorus compared to arsenic.

Key Concepts

Acid Strength

Acid strength refers to the ability of an acid to donate protons (H+) in a solution. Stronger acids dissociate more completely in water, resulting in a higher concentration of H+ ions. The strength of an acid is often influenced by its molecular structure, including the stability of the conjugate base formed after proton donation.

Conjugate Base Stability

The stability of a conjugate base plays a crucial role in determining acid strength. A more stable conjugate base is formed when the negative charge is delocalized or when electronegative atoms can stabilize the charge. In comparing acids, the one that forms a more stable conjugate base upon losing a proton is typically the stronger acid.

Comparative Analysis of Acids

When comparing two acids, factors such as electronegativity, atomic size, and resonance must be considered. For example, in the case of H3PO4 and H3AsO4, the central atom's electronegativity and the ability to stabilize the negative charge in the conjugate base (H2PO4- vs. H2AsO4-) will help determine which acid is stronger.