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Marek Svrcina

Is HC2H3O2 molecular or ionic?

Amanda Packer  Follow

Acetic acid …. CH3COOH …. for the most part acetic acid exists as discrete molecules. When dissolved in water and small fraction of the molecules ionize to make H+ and CH3COO^- ions, but not many. Acetic acid is a weak acid. When we use the term “weak” it means that only a fraction of the molecules ionize when dissolving.

CH3COOH(aq) <=> H+ + CH3COO^- …………… Ka = 1.76x10^-5
The small value of Ka (the equilibrium constant) indicates that the equilibrium lies far to the left, and that most of the non-ionized molecules stay molecules.

Incidentally, even a strong acid like HCl ionizes completely in water to make H+ ions and Cl- ions. Strong acids ionize completely. But you would not call HCl “ionic.” HCl has bonds with high covalent character exists as discrete molecules

Therefore, you would not refer to acetic acid as being “ionic”. It exists as discrete molecules with bonds with high covalent character.

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Butch Black  Follow

Water is a molecule and is not considered ionic. You could determine this in either of two ways. First way: note that the bonds in water are between nonmetals. Bonds between nonmetals are usually covalent and not ionic. Second way: Determine the degree to which the compound splits up into ions when it dissolves in water. Water hardly splits up at all, as indicated by a small equilibrium constant for its dissociation. Compounds that dissociate only a little or not at all are molecular and not ionic

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