Sonata in B flat for clavier

Most editions of Mozart’s piano sonatas include the same 18 three-movement sonatas. However, at least three early sonatas have been lost; only their incipits are known. The Sonata in F major, K. 547a, which is closely related to the Violin Sonata in F major, K. 547, consists of only two movements. The sonatas composed in 1774/75—K. 279–284—were known within the family as the “difficult sonatas” and form a set modeled on Joseph Haydn’s so-called Esterházy Sonatas Hob. XVI:21–26. The next series of sonatas was published in groups of three (K. 309–311 and K. 330–332), while those composed from late 1783 onward were published as individual works.