There's a little confusion in your question. "Formulae" implies there are multiple, but there's really only one chemical formula for sodium ethanoate:

CH₃COONa

This is the molecular formula, representing the actual number of atoms of each element in the compound.

Here's a breakdown:

* CH₃: This represents the methyl group (one carbon atom bonded to three hydrogen atoms).

* COO: This represents the carboxylate group (one carbon atom double-bonded to an oxygen atom and single-bonded to another oxygen atom, which is also bonded to a sodium atom).

* Na: This represents the sodium atom.

However, there are two common ways to write the formula:

* CH₃COONa (as mentioned above)

* NaCH₃COO (this is the preferred way when writing it as a salt in chemical reactions)

Both are equally valid and represent the same compound, which is also commonly known as sodium acetate.