Estimate the average bond energy in . The values of standard enthalpy of formation of , S(g) and F(g — Thermodynamics and Thermochemistry Chemistry Question
Question
Estimate the average $\text{S}-\text{F}$ bond energy in $\text{SF}_6$. The values of standard enthalpy of formation of $\text{SF}_6\text{(g)}$, S(g) and F(g) are –1100, 275 and 80 kJ/mol, respectively.
Answer: B
💡 Solution & Explanation
Total enthalpy of atomization for $\text{SF}_6 = \Delta H_f(\text{S,g}) + 6\Delta H_f(\text{F,g}) - \Delta H_f(\text{SF}_6, \text{g}) = 275 + 6(80) - (-1100) = 275 + 480 + 1100 = 1855\text{ kJ}$. Since $\text{SF}_6$ has 6 $\text{S}-\text{F}$ bonds, the average energy per bond is $1855 / 6 = 309.167\text{ kJ/mol}$.
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