Question

calculate the heat of reaction δh for the following reaction:
2 hcl(g) + br₂(g)→2 hbr(g) + cl₂(g)
you can find a table of bond energies by using the data button on the aleks toolbar.
round your answer to the nearest kj/mol.
□ (kj)/(mol)

Explanation:

To calculate the heat of reaction (\(\Delta H\)) using bond energies, we use the formula:
\(\Delta H = \sum (\text{bond energies of reactants broken}) - \sum (\text{bond energies of products formed})\)

Step 1: Identify bonds broken/formed

• Reactants: \(2\ \text{HCl}(g)\) (2 \( \text{H-Cl} \) bonds) and \(1\ \text{Br}_2(g)\) (1 \( \text{Br-Br} \) bond).
• Products: \(2\ \text{HBr}(g)\) (2 \( \text{H-Br} \) bonds) and \(1\ \text{Cl}_2(g)\) (1 \( \text{Cl-Cl} \) bond).

Step 2: Look up bond energies (from standard tables)

• \( \text{H-Cl} \): \(431\ \text{kJ/mol}\)
• \( \text{Br-Br} \): \(193\ \text{kJ/mol}\)
• \( \text{H-Br} \): \(366\ \text{kJ/mol}\)
• \( \text{Cl-Cl} \): \(243\ \text{kJ/mol}\)

Step 3: Calculate energy to break reactant bonds

• For \(2\ \text{HCl}\): \(2 \times 431 = 862\ \text{kJ/mol}\)
• For \(1\ \text{Br}_2\): \(1 \times 193 = 193\ \text{kJ/mol}\)
• Total (reactants): \(862 + 193 = 1055\ \text{kJ/mol}\)

Step 4: Calculate energy released to form product bonds

• For \(2\ \text{HBr}\): \(2 \times 366 = 732\ \text{kJ/mol}\)
• For \(1\ \text{Cl}_2\): \(1 \times 243 = 243\ \text{kJ/mol}\)
• Total (products): \(732 + 243 = 975\ \text{kJ/mol}\)

Step 5: Calculate \(\Delta H\)

\(\Delta H = 1055 - 975 = 80\ \text{kJ/mol}\)

Answer:

\(\boxed{80}\) (in \(\frac{\text{kJ}}{\text{mol}}\))