Explain why acid strength increases in the order HClO ₆ HClO_{2 6} HClO_{3 6} HClO₄.

Verified step by step guidance

1. Step 1: Understand the structure of oxyacids. Oxyacids are acids that contain hydrogen, oxygen, and another element (the central atom). In this case, the central atom is chlorine (Cl) in each of the acids HClO, HClO2, HClO3, and HClO4.
2. Step 2: Recognize the role of electronegativity and oxidation state. The strength of an oxyacid is influenced by the electronegativity of the central atom and its oxidation state. As the oxidation state of the central atom increases, the acid strength generally increases.
3. Step 3: Analyze the oxidation states of chlorine in each acid. Calculate the oxidation state of chlorine in each acid: HClO (Cl is +1), HClO2 (Cl is +3), HClO3 (Cl is +5), and HClO4 (Cl is +7).
4. Step 4: Relate oxidation state to acid strength. Higher oxidation states of chlorine result in a greater ability to stabilize the negative charge on the conjugate base after the acid donates a proton (H+). This stabilization makes the acid stronger.
5. Step 5: Conclude with the trend. As the oxidation state of chlorine increases from HClO to HClO4, the acid strength increases due to the increased ability of the central atom to stabilize the conjugate base, making HClO4 the strongest acid in the series.

Key Concepts

Acid Strength and Dissociation

Acid strength is determined by the degree to which an acid dissociates in solution to release protons (H+ ions). Stronger acids dissociate more completely, resulting in a higher concentration of H+ ions in solution. The ability of an acid to donate protons is influenced by its molecular structure and the stability of the resulting anion.

Oxidation State of Central Atom

In oxyacids, the oxidation state of the central atom (usually a nonmetal) plays a crucial role in determining acid strength. Higher oxidation states typically lead to stronger acids because they stabilize the negative charge on the conjugate base after dissociation. For example, in the series HClO, HClO2, HClO3, and HClO4, the central chlorine atom's increasing oxidation state enhances the acid's ability to donate protons.

Electronegative Atoms and Inductive Effect

The presence of electronegative atoms in an acid can influence its strength through the inductive effect. Electronegative atoms pull electron density away from the O-H bond, weakening it and making it easier for the acid to release a proton. In the case of the chlorous acids, the addition of more oxygen atoms increases the overall electronegativity, thereby enhancing the acid's strength as seen in the increasing order from HClO to HClO4.