Piano Sonata in Bb, movement 1 - Mozart

Context

• Classical style
• Piano had replaced harpsichord - capable of delicate dynamic effects
• This work was first published in 1784, as one of three sonatas

Structure

• Three movements - fast-slow-fast - sonata form
• Three main sections, each defined by key

Exposition

• Home key of Bb major
• First subject - bars 1-10
• Next 12 bars move into dominant key F major
• Starting in bar 23, Mozart presents the first of several ideas in this key (second subject group)
• Exposition ends with a codetta (bars 50-63) in which F major is affirmed by a succession of perfect cadences (bars 53-54, 57-59 and 62-63)

Development

• Bars 63-93
• Wider range of keys
• Begins with first subject in F major but soon passes through the keys of F minor, C minor, Bb major and G minor
• Seven bars of dominant preparation starting in bar 87 signal return of home key

Recapitulation

• Bar 93 - end
• Material from the exposition returns, now…