Little is known about the precise circumstances surrounding the composition of the sonata; unlike the earlier
Sonata in C major, K. 309/284b, it was little mentioned in his correspondence. The surviving manuscript was written using the same type of paper used for the
Symphony No. 31 in D major, K. 297/300a, which Mozart purchased while in Paris. The sonata is a rare minor key composition in
Mozart's catalogue. Composed alongside the
Violin Sonata No. 21 in E minor, K. 304/300c, it has been suggested that the sudden death of
Mozart's mother may have led to the more sombre mood found in these pieces. ==Structure==