Calculate the volume of hydrogen required for complete hydrogenation of 0.25 dm3 of ethyne at STP.
Hydrogenation of ethyne complete in 2 process:-
1) C2H2 + H2 = C2H4
2) C2H4 + H2 = C2H6
Now add this,
C2H2 + H2 = C2H6
Hence, for 1 mole hydrogenation of ethyne 2 mole of H2 is require
So, 22.4 L hydrogenation of C2H2,
2 × 22.4 L H2 is require
So, 0.25 L, hydrogenation of C2H2
2×0.25L of H2 is require
Hence 0.5 L OR 0.5 dm^3 volume of H2 is require
Note 1 L = 1dm^3