Using the data provided, calculate the multiple bond energy ( kJ mol -1. ) of a C ≡ C bond 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) longrightarrow C 2 H 2(g) ; Δ H=225 kJ mol -1 2 C (s) longrightarrow 2 C (g) ; Δ H=1410 kJ mol -1 H 2(g) longrightarrow 2 H (g) ; Δ H=330 kJ mol -1

Question

Using the data provided, calculate the multiple bond energy ( kJ mol -1. ) of a C ≡ C bond 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) longrightarrow C 2 H 2(g) ; Δ H=225 kJ mol -1 2 C (s) longrightarrow 2 C (g) ; Δ H=1410 kJ mol -1 H 2(g) longrightarrow 2 H (g) ; Δ H=330 kJ mol -1  (A) 1165 (B) 837 (C) 865 (D) 815

Tardigrade Admin · Accepted Answer

For calculation of C = C bond energy, we must first calculate dissociation energy of C 2 H 2 as C 2 H 2(g) longrightarrow 2 C (g)+2 H (g) ...(i) Using the given bond energies and enthalpies: C 2 H 2(g) longrightarrow 2 C (g)+2 H (g) ; Δ H=-225 kJ ...(ii) 2 C (s) longrightarrow 2 C (g) ; Δ H=1410 kJ ...(iii) H 2(g) longrightarrow 2 H (g) ; Δ H=330 kJ ...(iv) Adding Eqs. (ii), (iii) and (iv) gives Eq. (i). ⇒ C 2 H 2(g) longrightarrow 2 C (g)+2 H (g) ; Δ H=1515 kJ ⇒ 1515 kJ =2 ×( C - H ) BE +( C ≡ C ) BE =2 × 350+( C ≡ C ) BE ⇒ ( C ≡ C ) BE =1515-700=815 kJ / mol

Q. Using the data provided, calculate the multiple bond energy (kJmol−1 ) of a C≡C bond C2​H2​. That energy is (take the bond energy of a C−H bond as 350kJmol−1 ) 2C(s)+H2​(g)⟶C2​H2​(g);ΔH=225kJmol−1 2C(s)⟶2C(g);ΔH=1410kJmol−1 H2​(g)⟶2H(g);ΔH=330kJmol−1

1165

837

865

815