Is dealing with the amount of energy required to initiate a reaction?

The energy required to initiate a reaction is called activation energy not entropy.

We can say that the entropy of a mixture is how stable it is. The more difficult it is to separate the constituents of a mixture, the more entropy it contains.

Enthalpy (H) is a thermodynamic function of a system, equivalent to the sum of the internal energy of the system plus the product of its volume multiplied by the pressure exerted on it by its surroundings. :)