What is the formula of iodous acid? What is the ionic charge on I?
The correct answer and explanation is :
Correct Answer:
- Formula of iodous acid: HIO₂
- Ionic charge on iodine (I): +3
Explanation (300 words):
Iodous acid is one of the oxoacids of iodine, where iodine is bonded to oxygen and hydrogen atoms. The chemical formula of iodous acid is HIO₂, indicating it consists of one hydrogen (H), one iodine (I), and two oxygen (O) atoms.
To determine the oxidation state (ionic charge) of iodine, we analyze the compound’s structure and use typical oxidation numbers:
- Hydrogen (H) almost always has an oxidation number of +1.
- Oxygen (O) almost always has an oxidation number of −2.
Let the oxidation number of iodine (I) be x. Then we set up the equation for the total charge of the molecule (which is neutral, so it equals 0):
$$
(+1) + (x) + 2(−2) = 0
\Rightarrow 1 + x − 4 = 0
\Rightarrow x = +3
$$
Thus, the oxidation state—or ionic charge—of iodine in iodous acid is +3.
Iodous acid is part of a group of iodine oxoacids, each with different oxidation states:
- Hypoiodous acid (HIO): iodine is +1
- Iodous acid (HIO₂): iodine is +3
- Iodic acid (HIO₃): iodine is +5
- Periodic acid (HIO₄ or H₅IO₆): iodine is +7
These differences arise because iodine, being a halogen in group 17, can exhibit multiple oxidation states, particularly when bonded to electronegative oxygen atoms.
Iodous acid is relatively unstable and not commonly found in pure form. It exists primarily in aqueous solution and tends to disproportionate into other iodine compounds. Nonetheless, understanding its formula and oxidation state is important in acid-base chemistry, redox reactions, and the study of halogen oxoacids.