I've looked through several of these etudes, but havn't played a whole lot... some of them have a very distinct technique while some I'd say you'd only be able to tell after have finished playing it. op 39 #5 has double notes, and at one point has double notes in one hand while the same hand simultaneously plays a melody on top. #6 has very fast running passages, and the hands cross over, and there's big leaps. #7 has very awkward hand positions mainly for the right hand, while the left hand typically plays chords or octaves. The others in this set I'm not too sure; I have played #8 but havn't really found a technical study in it, mostly just for musicality. Op 39 #1 has running passages in the right hand, double notes, leaps in the left hand, pretty much a combination of nearly every technique... #3 is very awkward double notes, and has running notes in both hands. #6 has some repeated notes, massive leaps, and awkward motifs in the right hand at a very fast speed. #8 has double notes and leaps in the left hand, and #9 also has double notes, awkward fingerings, and leaps.... the other I'm not too sure.....
That was my vague interpretation of the techniques in most of the etudes..... may not be 100% on, but it's an idea.