[mass]

In an experiment a 0.02M solution of benzoic acid in 0.02M of HCL is provided (solution X).
The benzoic acid in X is unionized - explain why.

I don't understand why the benzoic acid would be unionized, is it just simply because it isn't protonated?

[Borek]

unionized = not dissociated = protonated

[mass]

unionized = not dissociated = protonated

what is the benzoic acid protonated by though?

[Arkcon]

unionized = not dissociated = protonated

what is the benzoic acid protonated by though?

Simple.  Bases are protonated by acids.  Very strong acids protonate water, for example, which can function as an acid or a base.  Compared to HCl, benzoic acid is a base.  If there was no HCl in the solution, benzoic acid would protonate the water, and would be an ion, and would dissolve.

[Borek]

Note: it is not benzoic ACID that gets protonated. It is benzoate anion that is base, that is protonated.

HBenzoate <-> H⁺ + Benzoate^-

This is weak acid, it dissociates only slightly. When you add excess H⁺, equilbrium moves to the left.

[mass]

Ah Yes I get it, thank you.