A friend of mine expressed her misplaced disgust upon seeing the kinetic energy equation, K = 1/2*m(v^2), on one of the Ap Chem packets. Regardless, the kinetic energy helps define the energy gained or lost in a reaction in the form of heat. If it helps, one can think of heat as the kinetic energy of molecules in random directions. If matter is energetic enough, it may undergo phase changes. This is also a form of internal energy, the work that is performed on the surroundings by a reaction becomes heat and is an example of the conservation of energy.