CH2=CH2( g)+H2( g)→CH3−CH3 ΔH=1(C=C)+4(C−H)+1(H−H)−1(C−C)−6(C−H)=1(C=C)+1(H−H)−1(C−C)−2(C−H) =615+435−347−2×414=1050−1175=−125 kJ
If at 298 ~K the bond energies of C- H, C- C, C= C and H- H bonds are respectively 414,347,615 and 435 ~kJ mol^-1, the value of enthalpy change for…
JEE Main 2003 — Chemistry Physical Chemistry
2003mcqmedium
If at 298 K the bond energies of C−H,C−C,C=C and H−H bonds are respectively 414,347,615 and 435 kJ mol−1, the value of enthalpy change for the reaction H2C=CH2( g)+H2( g)→H3C−CH3( g) at 298 K will be
Official previous-year question
Held on 30 Apr 2003 · Verified 6 Jul 2026.
Options
- A
−250 kJ
- B
+125 kJ
- C
−125 kJ
- D
+250 kJ
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