If at 298K the bond energies of C-H,C-C,C=C and H-H bonds are respectively 414,347,615 and 435kJ/mol . The value of enthalpy change for the reaction (CH)2=(CH)2 (. g .)+H2(g) arrow (CH)3-(CH)3 (. g .) at 298K will be :

Question

If at 298K the bond energies of C-H,C-C,C=C and H-H bonds are respectively 414,347,615 and 435kJ/mol . The value of enthalpy change for the reaction (CH)2=(CH)2 (. g .)+H2(g) arrow (CH)3-(CH)3 (. g .) at 298K will be : (A) -250kJ (B) +125kJ (C) -125kJ (D) +250k

Tardigrade Admin · Accepted Answer

ΔHR=HR-HP ΔHR=4× 414+615+435-[.6× 414+347]. ΔHR=-125kJ

Q. If at $298 K$ the bond energies of $C - H, C - C, C = C$ and $H - H$ bonds are respectively $414, 347, 615$ and $435 k J / m o l$ . The value of enthalpy change for the reaction $(C H)_{2} = (C H)_{2 (g)} + H_{2} (g) \to (C H)_{3} - (C H)_{3 (g)}$ at $298 K$ will be :

$- 250 k J$

$+ 125 k J$

$- 125 k J$

$+ 250 k$

$Δ H_{R} = H_{R} - H_{P}$
$Δ H_{R} = 4 \times 414 + 615 + 435 - [6 \times 414 + 347]$
$Δ H_{R} = - 125 k J$

Q. If at 298K the bond energies of C−H,C−C,C=C and H−H bonds are respectively 414,347,615 and 435kJ/mol . The value of enthalpy change for the reaction (CH)2​=(CH)2(g)​+H2​(g)→(CH)3​−(CH)3(g)​ at 298K will be :

−250kJ

+125kJ

−125kJ

+250k