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Can you explain to me bond energy and example question? Prefersbly not a simple one that wont help answering answers later on
Accepted Answer
Bond energy is the average amount of energy required to break a specific type of bond between two atoms in a gaseous state. It is an important concept in understanding the stability of molecules and the energetics of chemical reactions. Here's an example that goes beyond the basics:
Question:
Calculate the enthalpy change (ΔH) for the following reaction, using the bond energies provided:
CH4(g) + 2O2(g) → CO2(g) + 2H2O(g)
Bond Energies (kJ/mol):
C-H: 413, O=O: 498, C=O: 799, O-H: 463
Solution:
1. Break down the bonds in the reactants:
- 4 C-H bonds in CH4: 4
413 kJ/mol = 1652 kJ/mol
- 2 O=O bonds in 2O2: 2
498 kJ/mol = 996 kJ/mol
2. Form the bonds in the products:
- 2 C=O bonds in CO2: 2
799 kJ/mol = 1598 kJ/mol
- 4 O-H bonds in 2H2O: 4
463 kJ/mol = 1852 kJ/mol
3. Calculate the enthalpy change:
ΔH = (energy required to break bonds) - (energy released by forming bonds)
ΔH = (1652 + 996) - (1598 + 1852) = -802 kJ/mol
Explanation:
This calculation demonstrates how bond energies can be used to estimate the enthalpy change of a reaction. The positive values represent energy required to break bonds, while the negative values represent energy released when bonds form. In this case, the reaction is exothermic, as the enthalpy change is negative.
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