As depicted in Figure , α ~ 0 (purple) indicates negligible relationship between the enthalpy of surface reaction and the surface activation energy resulting in a 'flat' volcano, while a completely proportional relationship, α ~ 1.0 (red), forms a more symmetric volcano curve; values between zero and one form the interspersed curves: blue of α ~ 0.8, green of α ~ 0.6, yellow of α ~ 0.4, and orange of α ~ 0.2 all with an offset E 0 of 102 kJ/mole. The linear scaling relationships can be universal and consistent across different molecules , while other chemicals such as formic acid exhibit different linear scaling relationships across different transition metal groups of the periodic table . The Figure set of volcano curves are also defined by the condition that the surface energy of B* changes at twice the rate of the surface energy of A*, which is a ratio that can vary between surface chemistries and materials.