Here is a YouTube video of Chopin's Ballade No. 1 played by Synthesia:Between 5:14 to 5:15, it is evident that Chopin has used the notes F-B-D#-G#, in that particular order, to form a chord. The arrangement of this chord is identical to that of the "Tristan Chord" used in Wagner's Tristan und Isolde.[ Invalid YouTube link ]The same notes that the "Tristan Chord" consists of are played in succession between 4:03 to 4:04 in this video of the 2nd movement of Rachmaninoff's 2nd piano concerto.Can you list any other pieces that contain the "Tristan Chord"?