Question

calculate the volume of hydrogen required for complete hydrogenation of 0.25 dm3 of ethyne at STP

Answer 1

  C2H2 +  2H2 = C2H6  

 At STP  

1 vol + 2 vol = 1 vol

There fore  

0.25 dm3 C2H2 * 2/1=  

0.50 dm3 H2  

Answer 2

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