Ternary form, here we come. This mazurka begins in g minor, but a quick IAC after only 4 measures in B-flat Major complicates matters. The next section last for a full six measures, really pounding home a plagal cadence as we return to g-minor and then cadence, not once, not twice, but 3 times. We repeat this first section again, with the IAC in B-flat, then a return to g-minor, which ends on a solid PAC. I would consider this A section a parallel phrase group, although it is asymmetrical. Even though we have weak cadences to begin it (two IACs in relative major, and the plagal second cadence) , it does feel complete due to the strong pull of the g-minor PAC that ends it. This entire section serves as expositional material, as we introduce the main theme and only repeat it. Since we begin and end in the same key, and on a PAC to end, this is a simple ternary form. The B section draws us suddenly into B-flat major, continuing the triple meter feel of repeating something 2 twice before reaching a conclusion on the third attempt. This section is a complete phrase, with a half cadence after the first 6 measures, then a parallel section that ends on a PAC. This whole phrase is repeated again, making this B section feel very complete on it's own (thus making this piece ternary rather than binary). This section is developmental, as we take a key we hinted at before (B-flat) and explore it more fully for 24 measures. Between the end of the B section and the return of the A we have a wandering transitional-atory section that doesn't necessarily fit into either section, but serves as a small melody that brings us back to our original g-minor key. Now to end we have a full recapitulation of our A section. Since we have a full B section as well as the full recapitulation of the A section, this piece is definately ternary.
I love how Chopin uses the mazurka as a vehicle for such original music. The variety offered by the dance-like form pushes Chopin to creative heights. Love it!!!!