Question 21.7: Consider sulfurous acid, H2SO3. ⓐ Show its Lewis structure a...
Consider sulfurous acid, H_{2}SO_{3}.
ⓐ Show its Lewis structure and that of the HSO_{3}^{-} and SO_{3}^{2-} ions.
ⓑ How would its acid strength compare with that of H_{2}SO_{4}? H_{2}TeO_{3}?
ⓐ
Reread the discussion on writing Lewis structures in Chapter 7.
H-\overset{..}{\underset{..}{O}}-\overset{..}{\underset{\overset{|}{\underset{..}{:O:}} }{S}}-\overset{..}{\underset{..}{O}}-H (H-\overset{..}{\underset{..}{O}}-\overset{..}{\underset{\overset{|}{\underset{..}{:O:}} }{S}}-\overset{..}{\underset{..}{O:}} )^{-} (\overset{..}{\underset{..}{:O}}-\overset{..}{\underset{\overset{|}{\underset{..}{:O:}} }{S}}-\overset{..}{\underset{..}{O:}} )^{2-}
sulfurous acid hydrogen sulfite ion sulfite ion
ⓑ
1. Predict acid strength on the basis of electronegativity when the central atoms of the acids being compared are different.
H_{2}SO_{3} vs H_{2}TeO_{3}
S more electronegative than Te
H_{2}SO_{3} is a stronger acid than H_{2}TeO_{3}.
2. Predict acid strength on the basis of oxidation number when the central atoms of the acids being compared are identical.
H_{2}SO_{3} vs H_{2}SO_{4}
oxidation number of S: +4 oxidation number of S: +6
H_{2}SO_{4} is a stronger acid than H_{2}SO_{3} .