Just wondering if anyone could help me with the first question here?
I'm guessing it's something to do with how some reactions are endothermic and some are exothermic and so the energy produced in one is used to break the bonds from another?
Or something along those lines I just need a little clarifying, thanks in advancee
When the Enthalpy change(delta H) is negative the reaction is exothermic (i.e. more energy is released in forming new bonds than is absorbed when breaking old bonds) and when it is positive, the reaction is endothermic (i.e. more energy is absorbed in breaking old bonds than is released in forming new bonds).
When the Enthalpy change(delta H) is negative the reaction is exothermic (i.e. more energy is released in forming new bonds than is absorbed when breaking old bonds) and when it is positive, the reaction is endothermic (i.e. more energy is absorbed in breaking old bonds than is released in forming new bonds).
The enthalpy change indicates if energy is released by the forward reaction (exothermic, indicated by a negative value) or if energy is need in order for the forward reaction to take place (endothermic, indicated by a positive value). These values can be calculated by setting up a Hess equation: formation equation, combustion equation. Hess's law states that ''The enthalpy change accompanying a chemical change is independent of the route by which the chemical change occurs.''