Question

Write the resonance structures of formate ion. What do you infer regarding the relative
bond length values of two C-O bonds in it? Explain the reason.​

Answer 1

Answer:

The dissociation of Formic acid is explained in the diagram attached with the answer.

Please refer closely to the diagram when going through the answer.

Before studying the resonance structures of formate ion, let us know what are resonant structures,

Resonance structures are a set of two or more Lewis Structures that collectively describe the electronic bonding a single polyatomic species including fractional bonds and fractional charges. Resonance structures are capable of describing delocalized electrons that cannot be expressed by a single Lewis formula with an integer number of covalent bonds.

The dissociation can be described as follows:

C=O group due to -M effect pulls electron density, and forms structure (b).

Structure (a) & (b) are equal to each other so they result into structure (c), where both C-O bonds are of same length (i.e 1.272 ang) and negative charge is spread evely on both O atoms.

Answer 2

The resonance structure of the formate ion is attached below.

• The C=O group present in the formate ion pulls the electron density.

• This is due to the -M effect.

• Both structures are equal to each other.

• The length of the bond is also the same is both cases i.e 1.272 ang.

• The negative charge is spread evenly on both the O atoms.