Daca se reduce la jumatate, inseamna ca hidrogenul este in exces
Consideram x moli C2H2
a moli hidrogen
C2H2+ 2H2--->C2H6
x......2x.........x
H2----->H2
a-2x........a-2x
initial a+x
final a-x
(a+x)/2=a-x
a+x=2a-2x
a=3x
amestecul initial 4x
4x moli......x moli acetilena.......3x moli hidrogen
100...............%....................%
C2H2=25%
hidrogen=75%