Dissociation Energy

[Germar G 4F]

Why is the dissociation energy of a covalent bond, like N2, 932 kJ/mol and an ionic bond's, like NaCl, is -250 kJ/mol? (I wrote these down on my notes from the lecture). Since ionic bonds are stronger, wouldn't it have a much higher dissociation energy than N2? Why is it's dissociation energy negative?

[Casandra]

Why is the dissociation energy of a covalent bond, like N2, 932 kJ/mol and an ionic bond's, like NaCl, is -250 kJ/mol? (I wrote these down on my notes from the lecture). Since ionic bonds are stronger, wouldn't it have a much higher dissociation energy than N2? Why is it's dissociation energy negative?

Dissociation energy is negative because it is indicating that there is energy being released when the bond of NaCl, for example, is forming. Whereas the dissociation energy would be positive if energy was being taken in. In the lecture notes, the bond between NaCl is stronger and more stable than that of N2, the positive and negative values of the dissociation energy just indicate whether energy was released or absorbed.

[Shibhon_Shepard]

Okay, if the negative is releasing or absorbing energy what does the positive indicate?

[Elizabeth Kim 4E]

Dissociation energy is negative when the bond is releasing energy, and it is positive when it is absorbing energy