Questions: Use the molar bond enthalpy data in the table to estimate the value of ΔHrxn° for the equation CCl4(g) + 2 F2(g) → CF4(g) + 2 Cl2(g)

Transcript text: Use the molar bond enthalpy data in the table to estimate the value of $\Delta H_{\text {rxn }}^{\circ}$ for the equation \[ \mathrm{CCl}_{4}(\mathrm{~g})+2 \mathrm{~F}_{2}(\mathrm{~g}) \longrightarrow \mathrm{CF}_{4}(\mathrm{~g})+2 \mathrm{Cl}_{2}(\mathrm{~g}) \]

Solution

Solution Steps

Step 1: Calculate the total bond enthalpy of the reactants

The reactants are CCl₄ and 2F₂. CCl₄ has 4 C-Cl bonds. 2F₂ has 2 F-F bonds. Total bond enthalpy of reactants = 4 * 331 kJ/mol + 2 * 155 kJ/mol = 1634 kJ/mol

Step 2: Calculate the total bond enthalpy of the products

The products are CF₄ and 2Cl₂. CF₄ has 4 C-F bonds. 2Cl₂ has 2 Cl-Cl bonds. Total bond enthalpy of products = 4 * 439 kJ/mol + 2 * 243 kJ/mol = 2242 kJ/mol

Step 3: Calculate the enthalpy change of the reaction

ΔH_rxn = Total bond enthalpy of reactants - Total bond enthalpy of products ΔH_rxn = 1634 kJ/mol - 2242 kJ/mol = -608 kJ/mol