The finale of Mozart’s Sonata No. 9 in D major, K. 311, is a lively rondo in 6/8. Its main theme begins with a short pickup and decorative appoggiaturas, then unfolds in compact phrases above sustained chords and light bass responses. Quick scales and contrasting episodes repeatedly carry the music away from this theme. A written cadenza interrupts the movement before the familiar opening returns, and an extended final section brings the sonata to a firm, animated close.

The opening theme balances singing gestures with rapid sixteenth-note descents. The right hand alternates little ornamental pickups, repeated melodic notes, and short runs, while the left hand often leaves space between its supporting chords. Some phrases end with sharply articulated answers from both hands. As the first episode develops, the upper part moves through longer scales over lower broken chords grouped around the lilting 6/8 pulse.

A contrasting idea uses more sustained upper notes and a moving lower line. The texture then grows busier as the left hand takes up continuous sixteenths beneath high right-hand notes and descending runs. Brief sparse exchanges interrupt these fuller passages. Chromatic double notes and trills lead toward a return of the main tune, which brings back the opening’s small ornaments and recognizable phrase shapes.

The central episode introduces repeated upper notes over a rapid lower accompaniment, followed by figures that alternate between octave positions in the right hand. The left hand has its own rising and falling melodic line beneath them. Changes of register, accented notes, and chromatic shifts make this passage more unsettled. Decorated sequences eventually lead to descending running figures and a large chord held under a fermata.

The cadenza then leaves the left hand silent while the right hand plays a free sequence of flourishes. An Andante passage includes quick grouped runs and a trill. A Presto marking introduces an ascending chromatic scale, followed by an Adagio descent with ornaments and a ritardando. Tempo I restores the rondo theme and its accompaniment. Later passages revisit the earlier scales, sustained-note texture, and rapid left-hand figures before the coda brings another short appearance of the main idea and the final chordal close.

Interesting fact: The edition includes a specific instruction before the cadenza: the fermata chord is to be held for at least four measures, after which the cadenza follows without another pause. This creates a marked interruption in the otherwise continuous rondo motion.