Question

Given the balanced equation representing a reaction: `2NaCl -> 2Na + Cl_2`. What must happen to energy in the reaction to break the bonds in NaCl?

Answer 1

Well, a great deal of energy must be expended to break the strong ionic bond........

Explanation:

Certainly we could measure the enthalpy change for the following reaction:

`Na(s) + 1/2Cl_2(g) rarr NaCl(s) + Delta`, and in the reverse reaction, of course, the same amount of energy must be expended as was released when the ionic bond was formed:

`NaCl(s) + Delta rarr Na(s) + 1/2Cl_2(g)`

This goes back to the old principle we learn when we begin chemistry:

`"the breaking of bonds REQUIRES energy; the making"`
`"of bonds RELEASES energy."`

Are these ideas consistent with the principle of conservation of energy?