Using the data provided, calculate the multiple bond energy k J m o l - 1 of a C ≡ C bond in C 2 H 2 . That energy is (take the bond energy of a C - H bond as 350 k J m o l - 1 ) 2 C s → 2 C g ; ∆ H =

Question

Using the data provided, calculate the multiple bond energy $(k J m o l^{- 1})$ of a $C \equiv C$ bond in $C_{2} H_{2}$ . That energy is (take the bond energy of a $C - H$ bond as $350 k J m o l^{- 1}$ )

$2 C (s) \to 2 C (g ;)$ $∆ H = 1410 k J m o l^{- 1}$

$H_{2} (g) \to 2 H (g) :$ $∆ H = 330 k J m o l^{- 1}$

$2 C (s) + H_{2} (q) \to C_{2} H_{2}; ΔH = 225 {kJmol}^{- 1}$

TestHub · Accepted Answer

(i) 2 C s + H 2 g → H - C ≡ C - H ( g ) ∆ H = 225 k J m o l - 1 (ii) 2 C s → 2 C ( g ) ∆ H 1 = 1410 K J m o l - 1 i i i H 2 ( g ) → 2 H ( g ) ∆ H 2 = 330 K J m o l - 1 From equation (i) : 225 = ∆ H 1 + ∆ H 2 - [ 2 ∆ H C - H + ∆ H C ≡ C ] 225 = 1410 + 330 + 2 × 350 + ∆ H C ≡ C ] 225 = 1040 - ∆ H C ≡ C ∆ H C ≡ C = 1040 - 225 = 815 K J m o l - 1

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