Exercise 12 | Lewis Formulas

Chapter 7 - Lewis Formulas

Balance the following reaction and calculate its change in enthalpy ΔH⁰.

C₆H₅COOH + O₂→ CO₂ + H₂O

Data:

Bond energy (BE):

H-H = 436 kJ.mol^-1

C-H = 413 kJ.mol^-1

C-C = 347 kJ.mol^-1

C=C = 607 kJ.mol^-1

C-0 = 358 kJ.mol^-1

C=0 = 805 kJ.mol^-1

O-O = 204 kJ.mol^-1

O=O = 498 kJ.mol^-1

O-H = 464 kJ.mol^-1

See Solutions

Solution

2 C₆H₅COOH + 15 O₂→ 14 CO₂ + 6 H₂O

ΔH⁰ = 6 BE (C=C) + 8 BE (C-C) + 2 BE (C=O) + 2 BE (C-O) + 2 BE (O-H) + 10 BE (C-H) + 15 BE (O=O)
- 28 BE (C=O) – 12 BE (O-H)

= -6836 kJ.mol^-1