Didn't I answer that? Citric acid is a ternary organic strong acid. Monosodium citrate and disodium citrate each have two isomers, while trisodium citrate is equivalent to three-－COOH hydrogen ions all replaced by sodium.

There is only one structure, and the former is not reasonable. For sodium salts, we usually put sodium at the front. All the hydrogens on the three carboxyl groups of citric acid are replaced by sodium atoms. Moreover, the acidity of a hydroxyl group on the middle carbon atom is obviously not as good as that of carboxyl groups, so there are not so many isomers.

Chemical name: trisodium citrate (with two crystal waters)

Molecular formula: Na3C6H5O7.2H2O

Structural formula:

It's empty here, Ah Ah OH.

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NaOOC－CH2－C－CH2－COONa

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This is empty, COONa