For a composer who mastered many instruments, including piano and violin, Mozart – it may surprise some to learn – declared the viola to be his favorite, at least when he was performing chamber music. He chose to add a second viola in his sublime series of string quintets, and his only clarinet trio is indeed also a showpiece for viola.
Be all of that as it may, violinists can be (and are) grateful to Mozart, not just for three undisputed gems in the concerto category (as well as the incomparable double concerto for violin and viola he designated as a Sinfonia concertante), but also for nearly 20 mature sonatas for violin and piano. He wrote music for this instrumentation over the span of many years, beginning in his earliest days as a prodigy (with K. 6).
One of the last such works was composed during his Vienna years in 1785. K. 481 is in E-flat, the same key Mozart chose for that Sinfonia concertante (K. 364), for his first great Piano Concerto (No. 9, K. 271), and for the Symphony No. 39 (K. 543). The Sonata’s first movement is in (appropriately enough) sonata form, followed by a lyrical slow movement and a concluding set of variations.
Mozart, who had by this time moved on from the earlier convention of composing what was essentially a keyboard work with an optional violin part, offers each of the two players plenty of material, although the first edition (published by Franz Hoffmeister, the dedicatee of String Quartet No. 20, K. 499) describes it as a “sonata for fortepiano, or harpsichord, with violin accompaniment.”