Final answer:
Sulfinic acid is monoprotic with only one ionizable hydrogen atom in the hydroxyl group. The Lewis structure shows sulfur double bonded to oxygen and a hydroxyl group providing the acidic hydrogen. Other hydrogen atoms in the molecule do not readily ionize, making sulfinic acid monoprotic.
Step-by-step explanation:
Sulfinic acid is a monoprotic acid meaning it has only one ionizable hydrogen atom that can be released into solution. This is in contrast to polyprotic acids, which have multiple ionizable hydrogens, such as diprotic acids (e.g., H₂SO₄) that can donate two protons and triprotic acids (e.g., H₃PO₄) that can donate three protons in successive steps.
While drawing the Lewis structure of a sulfinic acid molecule, you will notice that it contains a sulfur atom double bonded to two oxygen atoms, and it has two other groups attached: a hydroxyl group (OH), which provides the acidic proton, and an alkyl or aryl group (R). The acidic hydrogen is the one attached to the oxygen in the hydroxyl group because oxygen can stabilize the negative charge after it loses the hydrogen as a proton (H+). The other hydrogen atoms, if present, are bound directly to the sulfur or to carbon in the R group and are not acidic as they do not readily dissociate.