Question

section iii: critical thinking 17. the polyatomic ion bromate, bro₃¹⁻, appears on the ion table, but the bromite ion does not. what would be the formula and charge for the bromite ion? write the formula for bromic acid and bromous acid

Explanation:

Step1: Determine bromite ion formula/charge

Polyatomic ions with "ate" and "ite" suffixes: "ite" has one less O than "ate". Bromate is $\ce{BrO3^-}$, so bromite should be $\ce{BrO2^-}$ (charge remains -1 as the central Br oxidation state logic: Br in $\ce{BrO3^-}$: let x be Br oxidation state, $x + 3(-2) = -1$ → $x = +5$; in $\ce{BrO2^-}$: $x + 2(-2) = -1$ → $x = +3$, consistent with "ite" having lower oxidation state, same charge for similar oxyanions of same central atom).

Step2: Bromic acid formula

Bromic acid is the acid of bromate ion. Acids from oxyanions: add $\ce{H^+}$ to balance charge. Bromate is $\ce{BrO3^-}$, so 1 $\ce{H^+}$ (charge +1) balances 1 $\ce{BrO3^-}$ (charge -1), formula $\ce{HBrO3}$.

Step3: Bromous acid formula

Bromous acid is the acid of bromite ion ($\ce{BrO2^-}$). Add $\ce{H^+}$: 1 $\ce{H^+}$ balances 1 $\ce{BrO2^-}$, formula $\ce{HBrO2}$.

Answer:

Bromite ion: $\boldsymbol{\ce{BrO2^-}}$ (charge -1)
Bromic acid: $\boldsymbol{\ce{HBrO3}}$
Bromous acid: $\boldsymbol{\ce{HBrO2}}$