Question

Use the data given below to construct a Born-Haber cycle to determine the bond energy of O2.

\Delta H°(kJ)
Na(s) --> Na(g) 107
Na(g) --> Na+(g) + e- 496
O(g) + e- --> O-(g) -141
O-(g) + e- --> O2-(g) 878
2 Na(s) + 1/2O2(g) --> Na2O(s) -416
2 Na+(g) + O2-(g) --> Na2O(s) -2608
Answer Options:
a. 426 kJ
b. 852 kJ
c. 498 kJ
d. 356 kJ
e. 249 kJ

Answer 1

To determine the bond energy of O2, we can use the Born-Haber cycle. By considering the enthalpy changes involved in the reaction, we can calculate the bond energy. The bond energy of O2 is found to be 2192 kJ/mol.

Step-by-step explanation:

To determine the bond energy of O2 using a Born-Haber cycle, we need to consider the enthalpy changes involved in the reaction. The enthalpy values given in the question can be used to construct the cycle. Here's how we can do it:

1. Start with Na(s) and convert it to Na(g) using the enthalpy change of 107 kJ.
2. Next, remove an electron from Na(g) to form Na+(g) using the enthalpy change of 496 kJ.
3. Then, add an electron to O(g) to form O-(g) with the enthalpy change of -141 kJ.
4. Further, add another electron to O-(g) to form O2-(g) with an enthalpy change of 878 kJ.
5. Now, combine 2 Na(s) with 1/2 O2(g) to form Na2O(s) with an enthalpy change of -416 kJ.
6. Lastly, combine 2 Na+(g) with O2-(g) to form Na2O(s) with an enthalpy change of -2608 kJ.

The bond energy of O2 can be calculated by finding the difference between the energy required to break the reactant bonds and the energy released to form the product bonds. In this case, the bond energy of O2 is (-416 kJ) - (-2608 kJ) = 2192 kJ/mol.