Use the table to answer the question.

Question

Reaction CH4 + 4Cl2 → CCl4 + 4HCl
Reactants Products
Bonds Present
4 H–C

4 Cl–Cl

4 C–Cl

4 H–Cl

Energy of Bonds Broken (Reactants) / Formed (Products)

4 × 411 kJ/mol

4 × 242 kJ/mol

4 × 327 kJ/mol

4 × 427 kJ/mol

Which statement about the change in bond energy of this reaction is correct?

(1 point)
Responses

The reaction is endothermic because the total bond energy of the reactants is greater than the total bond energy of the products.
The reaction is endothermic because the total bond energy of the reactants is greater than the total bond energy of the products.

The reaction is exothermic because the energy of each bond in the reactants is greater than the energy of a bond in the products.
The reaction is exothermic because the energy of each bond in the reactants is greater than the energy of a bond in the products.

The reaction is exothermic because the total bond energy of the reactants is less than the total bond energy of the products.
The reaction is exothermic because the total bond energy of the reactants is less than the total bond energy of the products.

The reaction is endothermic because the energy of each bond in the reactants is less than the energy of a bond in the products.
The reaction is endothermic because the energy of each bond in the reactants is less than the energy of a bond in the products.

Answer 1

To determine whether the reaction is endothermic or exothermic, we need to calculate the total bond energy for both the reactants and the products.

Step 1: Calculate the total bond energy for the reactants:

• Bonds in reactants:
  • 4 H–C bonds = 4 × 411 kJ/mol = 1644 kJ
  • 4 Cl–Cl bonds = 4 × 242 kJ/mol = 968 kJ
• Total bond energy of reactants:
  \( 1644 , \text{kJ} + 968 , \text{kJ} = 2612 , \text{kJ} \)

Step 2: Calculate the total bond energy for the products:

• Bonds in products:
  • 4 C–Cl bonds = 4 × 327 kJ/mol = 1308 kJ
  • 4 H–Cl bonds = 4 × 427 kJ/mol = 1708 kJ
• Total bond energy of products:
  \( 1308 , \text{kJ} + 1708 , \text{kJ} = 3016 , \text{kJ} \)

Step 3: Compare the total bond energies:

• Total bond energy of reactants (2612 kJ) is less than the total bond energy of products (3016 kJ).

Conclusion: Since the total bond energy of the reactants is less than that of the products, energy is absorbed during the reaction, making the reaction endothermic. Therefore, the correct response is:

The reaction is endothermic because the total bond energy of the reactants is less than the total bond energy of the products.