Question

Use average bond energies to calculate Δrh for the combustion of methanol. CH₃OH (g) 32O₂(g)→CO₂(g) 2H₂O(g) average bond energies bond bond energy ( kjmol-1 ) h-c 414 h-o 464 c-c 347 c-o 360 c=o in CO₂ 799 o=o 498?

Answer 1

To calculate ΔH for the combustion of methanol, use the average bond energies of the reactants and products. The overall enthalpy change can be calculated by subtracting the energy required to break the bonds from the energy released when the bonds form. In this case, ΔH is approximately -601 kJ/mol.

Step-by-step explanation:

To calculate the enthalpy change (ΔH) for the combustion of methanol (CH₃OH), we can use average bond energies.

1. First, let's find the total energy required to break all the bonds in the reactants. The bonds to break are: 4 C-H bonds (415 kJ/mol), 1 C-O bond (360 kJ/mol), and 1 O-H bond (427 kJ/mol).
2. Next, let's find the total energy released when all the bonds in the products form. The bonds to form are: 2 C=O bonds (2x799 kJ/mol) and 4 O-H bonds (4x464 kJ/mol).
3. Finally, subtract the energy released from the energy required to find the overall enthalpy change. Calculate ΔH = (Energy released - Energy required).

Using the given bond energies, the calculations would be: ΔH = (2x799 + 4x464) - (4x415 + 1x360 + 1x427) = -601 kJ/mol.