Schubert begins with a simple I - V7 - I progression in E-flat major. However, he quickly introduces chromatic passing tones within the scales to blur the lines of the key.
Using the pivot between G-flat and F-sharp to bridge distant keys. schubert impromptu op 90 no 2 harmonic analysis
The piece follows a form with a substantial Coda. Section A: E-flat Major (perpetual motion triplet scales). Section B: B-minor (the dramatic "Trio" section). Section A': Return to E-flat Major. Coda: E-flat Minor (a tragic reversal of the opening). Section A: The Fluidity of E-flat Major Schubert begins with a simple I - V7