Using the data provided, calculate the multiple bond energy ( kJ mol − 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 kJ mol − 1 ) 2 C ( s ) + H 2 (

Question

Using the data provided, calculate the multiple bond energy ( kJ mol − 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 kJ mol − 1 ) 2 C ( s ) + H 2 ​ ( g ) ⟶ HC = CH ( g ) ; Δ H = 225 kJ mol − 1 2 C ( s ) ⟶ 2 C ( g ) ; Δ H = 1410 kJ mol − 1 H 2 ​ ( g ) ⟶ 2 H ( g ) ; Δ H = 330 kJ mol − 1

TestHub · Accepted Answer

(i) 2 C ( s ) + H 2 ​ ( g ) ⟶ H − C ≡ C − H ( g ) Δ H = 225 kJ mol − 1 (ii) 2 C ( s ) ⟶ 2 C ( g ) Δ H = 1410 kJ mol − 1 (iii) H 2 ​ (g) ⟶ 2 H (g) Δ H = 330 kJ mol − 1 From equation (i) : 225 = [ 2 × Δ H C ( s ) ⟶ C ( g ) ​ + 1 × BE H − H ​ ] − [ 2 × BE C − H ​ + 1 × BE C ≡ C ​ ] 225 = [ 1410 + 1 × 330 ] − [ 2 × 350 + 1 × BE C ≡ C ​ ] 225 = [ 1410 + 330 ] − [ 700 + BE C ≡ C ​ ] 225 = 1740 − 700 − BE C ≡ C ​ BE C ≡ C ​ = 815 kJ mol − 1 ​

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