Question

click the \investigation\ tab and break all the bonds in the reactants. then, create all the bonds in the products. note the energy changes throughout the process. enter the correct answer in the box. the δh value for ch₄ + 2 o₂ → co₂ + 2 h₂o is kj/mol.

Explanation:

Step1: Recall Bond Energy Values

We need bond energies for \( C - H \), \( O = O \), \( C = O \) (in \( CO_2 \)), and \( O - H \) (in \( H_2O \)). Typical values: \( C - H = 413 \, \text{kJ/mol} \), \( O = O = 498 \, \text{kJ/mol} \), \( C = O = 799 \, \text{kJ/mol} \), \( O - H = 463 \, \text{kJ/mol} \).

Step2: Calculate Energy to Break Bonds (Reactants)

For \( CH_4 \): 4 \( C - H \) bonds. Energy = \( 4 \times 413 = 1652 \, \text{kJ/mol} \).
For \( 2 O_2 \): 2 \( O = O \) bonds. Energy = \( 2 \times 498 = 996 \, \text{kJ/mol} \).
Total energy to break bonds: \( 1652 + 996 = 2648 \, \text{kJ/mol} \).

Step3: Calculate Energy Released by Forming Bonds (Products)

For \( CO_2 \): 2 \( C = O \) bonds. Energy = \( 2 \times 799 = 1598 \, \text{kJ/mol} \).
For \( 2 H_2O \): 4 \( O - H \) bonds (each \( H_2O \) has 2 \( O - H \)). Energy = \( 4 \times 463 = 1852 \, \text{kJ/mol} \).
Total energy released: \( 1598 + 1852 = 3450 \, \text{kJ/mol} \).

Step4: Calculate \( \Delta H \)

\( \Delta H = \) Energy to break bonds \( - \) Energy released by forming bonds.
\( \Delta H = 2648 - 3450 = -802 \, \text{kJ/mol} \).

Answer:

\(-802\)