Arrange the following substances in order from weakest to strongest acid: HClO3, HOI, HBrO2, HClO2, HIO2.

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Question restatement: Arrange the following substances in order from weakest to strongest acid: HOI, HIO2, HBrO2, HClO2, HClO3.

First, consider the general rules for oxoacids of halogens: adding more oxygen atoms (increasing oxidation state of the central halogen) tends to increase acidity because the conjugate base is stabilized by delocalizing negative charge over more O atoms. Also, for a given oxidation state, a more electronegative central atom (e.g., Cl vs Br vs I) stabilizes the conjugate base better through inductive effects, generally increasing acidity.

Option breakdown and reasoning:
- HOI (hypoiodous acid): Iodine is less electronegative and has the lowest oxidation state among the listed species, and it also has the fewest oxygens. This tends to make HOI the weakest acid in this set, since the conjugate base IO− is less stabilized.
- HIO2 (iodosoic acid): This adds an extra oxygen compared to HOI, raising the oxidation state of iodine. The presence of an additional oxo group increases acidity relative to HOI because the conjugate base (IO2−) is better stabilized by resonance with more oxygens.
- HBrO2 (bromous acid): Bromine is more electronegative than iodine, and HBrO2 has the same oxidation state (+3) as HIO2 but with a more electronegative center. This generally makes HBrO2 a stronger acid than HIO2 due to greater stabilization of the conjugate base via inductive effect from Br.
- HClO2 (chlorous acid): Chlorine is more electronegative than bromine, and HClO2 has Cl in the +3 oxidation state with two oxygens. Compared to HBrO2, the higher electronegativity of Cl tends to stabilize the conjugate base better, making HClO2 stronger than HBrO2.
- HClO3 (chloric acid): This has chlorine in the +5 oxidation state with three oxygens, which markedly increases acidity. It typically represents the strongest acid among the listed oxoacids due to both higher oxidation state and substantial resonance stabilization in the conjugate base.

Putting it together, the weakest to strongest order is:
HOI < HIO2 < HBrO2 < HClO2 < HClO3

Notes on the absence of other options: The dataset provided does not include a separate list of multiple-choice options to compare against, so the explanation focuses on validating the single stated ordering by applying the general trends for oxoacids of halogens. If alternative options were present, each would be weighed against these same principles (oxidation state, number of oxygens, and central atom electronegativity) to determine relative acidity.

CHEM 1220 SP2025 (18215) CHEM 1220 Practice Exam #3 v1 (16.6 - 16.10, 17.1 - 17.3)- Requires Respondus LockDown Browser

Arrange the following substances in order from weakest to strongest acid: HClO3, HOI, HBrO2, HClO2, HIO2.

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