# How do I rationalize this interesting chord in Mozart K. 331?

Lately I've started learning some basic music theory and I have been trying to rationalize some of the interesting chords I have heard of from famous pieces. Here is an example of which I am not sure if my understanding is correct.

Below are bar 11-12 from Mozart's Piano Sonata No.11 in A major, K.331. I have marked the chords using Roman numeral notations.

The blue text shows a naive marking. To me the ♯iv° chord gives a warm and sweet shifting feeling. I found that if I think of it as an applied chord (by tonicizing V) then the last three chords becomes a (vii° - IV - I) progression. If this is the case I was wondering how come the IV chord, as a pre-dominant chord, appears after the dominant chord vii° instead of before it? Why would the progression still sound inevitable when the strong dominant -> tonic progression is broken?

Per @Dekkadeci's answer I revised the analysis as follows. The final three-chord progression simultaneously resolves two tension (cadential I chord to V, and on the V scale, dominant vii° to tonic I.

If this is the case I was wondering how come the IV chord, as a pre-dominant chord, appears after the dominant chord vii° instead of before it? Why would the progression still sound inevitable when the strong dominant -> tonic progression is broken?

Due to the E as a root instead of an A, the second last chord is not formally a I or a plain IV/V chord, but it is actually a I 6/4 chord. The I 6/4 chord is treated as a pre-dominant chord that must be immediately followed by a dominant-function chord (often V, just like the last chord). Its pre-dominant function is so strong that one of the theory books I was told to use in harmony class labels it as V 6/4 instead.

(I also believe that the "#iv° 6" is actually vii° 6 of V.)

• Great answer! It's easy to ignore chord inversions because they often don't make too much of a difference to the overall harmony, but this is a perfect example of where it absolutely does! Commented Mar 8, 2017 at 18:18

You ask how to rationalise the progression. Here's how. It's a bare-bones B7, the dominant of the following chord, E, to which it resolves, delayed by a suspension. There's no room for all the notes of B7 in 3-part texture, but that's no reason to analyse it as something unnecessarily complicated.

• Pretty well what I thought...
– Tim
Commented Mar 8, 2017 at 12:00
• Hi Laurence, thanks for answering. However, I think that your analysis is not necessarily simpler than mine, although I do admit I tend to use big words as I just started learning :) . Your "bare-bones B7 with 3-part texture (and no root)" is basically explaining why vii° has a dominant function and your "the dominant of the following chord" is just my "tonicization". So to me the key part is why the IV/V chord was treated as a dissonance to be resolved, and as Dekkadeci has explained, it's because it happens to be a I 6/4 cadential chord.
– xzhu
Commented Mar 8, 2017 at 17:51
• the question isn't about the diminished chord, it's about the A/E chord. Analysing the dim chord as a B7 would still leave OP's question hanging, if anything more strongly. The question is why have a (#vi°) followed immediately by an I chord? The question then becomes Why would you have a II7 immediately followed by a I chord i.e. the same question. Commented Mar 8, 2017 at 18:05
• You're really not answering the question Laurence. I'll give you some time to clean if up and actually answer the question, but answer posts need to answer the question it this is more of a comment about something in the question.
– Dom
Commented Mar 8, 2017 at 18:29
• The question was how to rationalise the chord. I told him. I shall edit my answer to make this even more clear. Sorry if the answer wasn't complicated enough for some of you! Commented Mar 8, 2017 at 21:56

I'm not exactly qualified to give you the classical language answer but conceptually I hope I point you in the right direction. I had to look up the difference between an appogiatura, a suspension etc. etc. In Jazz we tend to call all resolving non chord tones suspensions, but I'm pretty sure in classical music a suspension has to come directly from the previous chord rather than be just any resolving non chord tone (which I believe in classical is strictly an "apogiatura".) I could be wrong with my terminology here, but hopefully that won't bog you down; the point is I'm talking about resolving non-chord tones!

Anyway, you are right that the diminished chord is absolutely tonicizing the V. The reason the A chord in its second inversion works here is that it ends up sounding like a suspended E chord, rather than an A chord.

The diminished chord resolves to the E in the bass, and then the the A and C# are apogiatura that resolve downwards to an E chord (it has a certain plagal cadence feel to it, but it's really an apogiatura.). To give an example without modulation, check this crappy midi thing I just whipped up http://onlinesequencer.net/425519 . It's progression ending in a perfect cadence in A, but the ending I chord has resolving D and F# in it.

To illustrate the point, I added an F# apogiatura to the passage you gave. http://onlinesequencer.net/425524. The point is, an F# obviously isn't in an A chord, but doesn't sound at all out of place here; it's performing the same function as the A and the C# resolving downwards to the E chord.

You could also put a B above the E in the bass and not change the harmony (although it's a bit of an ugly voicing).

• Classical theory has the concept of an 'unprepared suspension'. Or call it an appoggiatura if you prefer. Commented Mar 15, 2017 at 10:33

The second chord could easily be the leading tone chord with the E functioning like an escape tone. That big jump up and the step down is typical of an escape tone.

The d sharp that resolves to an e in bar two gives the very real impression of a leading tone resolving, Im thinking E major. The notes in the top two voices of the last beat just look like suspensions from the previous beat