Mozart, Piano Concerto in A Major, K 288, second movement, mm. 1-12
m. 1- i
m. 2- iv43, V65
m. 3- i, ii dim. 6
m. 4- V64-53
m. 5- VI6, viihd7/III
m. 6- III 2#-3, i
m. 7- IV65, V6
m. 8- I4-#3, VI
m. 9- N6
m. 11- V864-753
m. 12- i
-First phrase 4 measures (2+2), (m.1-m.4) HC, we could call this section A
-Second phrase 8 measures (2+2+2+2), (m.5-m.12) PAC, we could call this section A'
There are only 2 phrases in this excerpt. On the end of the first phrase, there is a HC in measure 4, and the next cadence is on the end of the second phrase in measure 12. Why can't we say that there is a third phrase in the middle? Because, the third phrase would have to finish at measure 8 which is I64, VI can not be a CADENCE!!! Harmonic rhythm does not stop, it keeps going. Measure 9 looks (for some people, but not for me) like the beginning of the "third" phrase because it has the same rhythmic motive in both hands, but we have to follow the harmonic rhythm. A' is longer than A because Mozart was playing around with the motive and was expanding the second phrase with some modal mixture.
In measure 9 and 10, the roman numeral N6 is very AMBIGUOUS (I’ve never heard this word before...and I do not know if you can use it in this case). Mozart prepares listeners with I and VI and then N6 in the same rhythm in the beginning before the whole measure and in the next measure there is an N6 arpeggio!!! That is the culmination of the second phrase, and right before big V864-753 to i.
I wish that I could play this very interesting piece. The good thing is that this section (m.1-m.12) is an introduction, a PIANO SOLO, so you could play with a lot of espressivo, ritardando, use a different colors for the phrases or what ever you like, but still in the Mozart style!!! I would play this as I explained in my phrases and sub phrases, so the audience can hear it very clear. In the second phrase I'd start in piano dynamic and build thru the measures till measure 9 ( N6) and in m. 10 bid crescendo to the V chord, decrescendo i.