Answer
The estimated change in energy (ΔE) for the combustion of one mole of acetylene is -1112 kJ/mol.
Work Step by Step
Given information:
- Combustion reaction: C2H2(g) + (5/2)O2(g) → 2CO2(g) + H2O(g)
Step 1: Calculate the total bond energy of the reactants.
Bond energies:
- C≡C bond: 839 kJ/mol
- C-H bond: 413 kJ/mol
- O=O bond: 498 kJ/mol
Total bond energy of the reactants:
1 × C≡C bond: 1 × 839 = 839 kJ/mol
2 × C-H bond: 2 × 413 = 826 kJ/mol
(5/2) × O=O bond: (5/2) × 498 = 1495 kJ/mol
Total bond energy of the reactants = 839 + 826 + 1245 = 2910 kJ/mol
Step 2: Calculate the total bond energy of the products.
Bond energies:
- C=O bond: 799 kJ/mol
- O-H bond: 463 kJ/mol
Total bond energy of the products:
2 x 2 × C=O bond: 4 × 799 = 3196 kJ/mol
2 × O-H bond: 2 × 463 = 926 kJ/mol
Total bond energy of the products = 3196 + 926 = 4122 kJ/mol
Step 3: Calculate the change in energy (ΔE).
ΔE = Total bond energy of the products - Total bond energy of the reactants
ΔE = 4122 kJ/mol - 2910 kJ/mol = -1112 kJ/mol
Therefore, the estimated change in energy (ΔE) for the combustion of one mole of acetylene is -112 kJ/mol.
