Solve 49 If bond energy of C≡C, C-H, O=O, C=O O-H bond is 800, 410, - Chemistry - Thermodynamics

Question

Solve

49 If bond energy of C ≡ C, C-H, O=O, C=O
& O-H bond is 800, 410, 500, 700 & 430 kJ / mol
respectively, then calorific value (kJ/gm) of ethyne is

(1) 25 28
(2) 30 38
(3) 790
(4) 303

Vartika Jain · Accepted Answer

Dear Student,

2HC≡CH + 5O2 → 4CO2 + 2H2O∆H=[∑(reactant bond energies)-∑(product bond energies)]       =[(4BEC-H+2BEC≡C + 5BEO=O) - (8BEC=O + 4BEO-H)]       =[(4×410+2×800+5×500) -(8×700+4×430)]       =[5740-7320]       =-1580 kJ/molThis means 2 mol of ethyne gives 1580 kJ of heatand 2 mol=26×2= 52 g of ethyneSo, 52 g of ethyne gives 1580 kJ of heatHence, 1 g of ethyne gives 158052=30
38 kJ/gThe correct answer is (2)

Solve 49. If bond energy of C ≡ C, C-H, O=O, C=O & O-H bond is 800, 410, 500, 700 & 430 kJ / mol respectively, then calorific value (kJ/gm) of ethyne is (1) 25.28 (2) 30.38 (3) 790 (4) 303

Solve

49. If bond energy of C $\equiv$ C, C-H, O=O, C=O & O-H bond is 800, 410, 500, 700 & 430 kJ / mol respectively, then calorific value (kJ/gm) of ethyne is

(1) 25.28
(2) 30.38
(3) 790
(4) 303