The Konzertstück in F minor for Piano and Orchestra, Op. 79, J. 282, was written by Carl Maria von Weber, and he started work on it in 1815, and completed it on the morning of the premiere of which opera, with spoken dialogue in three acts?
Konzertstück in F minor (Weber):  He started work on it in 1815, and completed it on the morning of the premiere of his opera "Der Freischütz", 18 June 1821.
i don't know