Question

Question #d81d0

Answer 1

The sulfate ion should have shorter sulfur-oxygen bonds than a sulfite ion.

Explanation:

The sulfite ion is a resonance hybrid of three equivalent contributing structures.

The bond orders of the `"S-O"` bonds in any one contributor are 2, 1, and 1.

The bond orders of the `"S-O"` bonds in the hybrid are an average of these numbers.

`BO =`2 + 1 +1)/3 = 4/3 = 1.33#

The sulfate ion is a resonance hybrid of six equivalent contributing structures.

The bond orders of the `"S-O"` bonds in any one contributor are 2, 2, 1, and 1.

The bond orders of the `"S-O"` bonds in the hybrid are an average of these numbers.

`BO = (2 + 2 + 1 +1)/4 = 6/4 = 1.50`

The greater the bond order, the shorter the bond length.

The `"S-O"` bond order is greater in the sulfate ion, so sulfate ions should have shorter `"S-O"` bonds.

Experiments confirm this prediction.

The measured `"S-O"` bond lengths are 149 pm in sulfate ion and 151 pm in sulfite ion.