dr. donald showalter. in this reaction, the reacting materials are potassium permanganate, this dark purple solid on this screen, and glycerine, this thick liquid. now, let's see what happens when we mix them. i'll put the glycerine onto the permanganate. there's some smoke coming out. oh! look at the flame! that reaction certainly releases energy, doesn't it? what happened is that glycerine is a combustible organic liquid and potassium permanganate is a concentrated source of oxygen. so when the two come in contact, they ignite spontaneously. so this kind of chemical reaction releases energy. the key word is release. this is the type of reaction we call exothermic. in an exothermic reaction, the reactants have relatively high energy. the energy is depicted here in kilojoules. the products of the reaction have a lower energy. as the reaction proceeds downhill from high energy to low energy, reactants are converted to products, and energy is released by the system-- in this case, 300 kilojoules per mole rea