Roman Numeral Analysis: Piano Sonata in C Major K. 545 - Rondo, W. A. Mozart
m. 41-48a: in key of vi, (a minor)
m. 41-43: i64, V7 (counting D in previous measure), i6
m. 44-45: V43 (counting D in previous measure), viidiminished, i, i6, viidiminished/iv
m. 46-48a: iv, iv6, (VI6), N6, V64-53, i
Mozart utilizes some interesting musical and compositional techniques in m. 41-48 of his Rondo from Piano Sonata in C Major K. 545. First, the harmony changes form measure 41-43 exhibit changes in harmony that go across measures due to the left and right hands exchanging motives and alternating when each hand plays, creating a syncopation of the harmony change. Therefore, the harmony actually changes before the downbeat. For example, the harmony in m. 42 begins the first beat with V7 (V7 because of B and D in the second beat of m. 41), but the harmony changes to i6 (i6 because of the C and A in the left hand of the next measure, m. 43) on the second beat of that measure. Mozart is changing the harmony when the listener does not expect it to change.
Next, m. 44-46’s quickly changing harmonies and the right hand’s sixteenth notes which create suspension of harmonies on every eighth note beat make forward motion towards the perfect authentic cadence in m. 47-48. Also, the left hand’s lowest eighth notes and the sixteenth notes of the right hand in the same passage create an inwards contrary motion (from first beat of m. 44 to the fourth eighth note beat of m. 46) to approach the N6 of m. 47 and add to the musical tension of the harmonic and rhythmic forward motion created by the passage, which is also aided by a small crescendo (m. 46).
Finally, the N6 in m. 47 acts as a predominant to V64-53. The N6 is approached by a iv6, which often happens when approaching an N6 chord. Regarding the melodic line and the resolution of leading tones, the ra of N6, approached by fa – me from the iv6 in m. 46, resolves in the cadence to do, ti and back to do (m. 47-48). N6 chords conventionally go from ra to ti and then resolve to do, thus using the harmonies N6, V(7), I in the process. However, it is not uncommon in to fill in the space in between the ra and ti with do, creating a pleasant, stepwise ra – do – ti – do motion as seen in this Mozart Rondo. This extra do also creates a passing harmony in between the N6 and the V(7), usually V64 or viifulldiminished7/V. Other than the left hand’s fairly large jump from D4 and F4 to E3 and C4 in m. 47, there is nothing unusual about the cadence, for it resolves properly in regards to proper resolution of leading tones and harmonic progression.