The bond energies of C-C , C=C , H-H and C-H linkages are 350, 600, 400 and 410 kJ/mol respectively. The heat of hydrogenation of ethylene is

Question

The bond energies of C-C , C=C , H-H and C-H linkages are 350, 600, 400 and 410 kJ/mol respectively. The heat of hydrogenation of ethylene is (A)  -170 kJ mol-1  (B)  -260 kJ mol-1  (C)  -400 kJ mol-1  (D)  -450 kJ mol-1

Tardigrade Admin · Accepted Answer

H- oversetH mathop overset| mathopC = oversetH mathop overset| mathopC -H+H-H→ H- undersetH mathop underset| mathop oversetH mathop overset| mathopC - undersetH mathop underset| mathop oversetH mathop overset| mathopC -H Δ Hreaction= Sigma BE text(Reactants)- Sigma textBE(Products) =[BE(4C-H)+BE(C=C)+BE(H-H)] -[BE (6C-H)+BE(C-C)] =BE(C=C)+BE(H-H)-BE(2C-H) -BE(C-C) =600+400-2× 410-350 =1000-1170=-170kJ mol-1

Q. The bond energies of $C - C$ , $C = C$ , $H - H$ and $C - H$ linkages are 350, 600, 400 and 410 kJ/mol respectively. The heat of hydrogenation of ethylene is

$- 170 k J m o l^{- 1}$

$- 260 k J m o l^{- 1}$

$- 400 k J m o l^{- 1}$

$- 450 k J m o l^{- 1}$

Q. The bond energies of C−C , C=C , H−H and C−H linkages are 350, 600, 400 and 410 kJ/mol respectively. The heat of hydrogenation of ethylene is

−170kJmol−1

−260kJmol−1

−400kJmol−1

−450kJmol−1

H−C∣H=C∣H−H+H−H→H−H∣C∣H​​−H∣C∣H​​−H ΔHreaction​=ΣBE(Reactants)-ΣBE(Products) =[BE(4C−H)+BE(C=C)+BE(H−H)] −[BE(6C−H)+BE(C−C)] =BE(C=C)+BE(H−H)−BE(2C−H) −BE(C−C) =600+400−2×410−350 =1000−1170=−170kJmol−1

Q. The bond energies of $C - C$ , $C = C$ , $H - H$ and $C - H$ linkages are 350, 600, 400 and 410 kJ/mol respectively. The heat of hydrogenation of ethylene is

$- 170 k J m o l^{- 1}$

$- 260 k J m o l^{- 1}$

$- 400 k J m o l^{- 1}$

$- 450 k J m o l^{- 1}$