The opening screen of topics in Science Volume 2 provides access to three sections describing the underlaing processess of phase equilibrium, the meaning of reaction constant and the explenation of basic thermodynamic functions.

The 3D animation on the left describes the formation of a molecule C, the collision product of molecule A and B. Note the formation of an 'activated complex' an unstable entity and an intermediary product of the A + B -> C reaction.

Chemical or physical transformations are associated with changes in the energy content (Enthalpy - H) and the degree of order (Entropy -S). For example the physical transformation of ice into water involves increase in Enthalpy and Entropy. Water contains more energy (has a higher Enthalpy), mostly in the form of kinetic energy of water molecules. Water is also less ordered then the solid lattice of ice. It therefore has a greater Entropy.

please click the animation controls

The concentrations of products and reactants change as the forward and reverse reactions negotiate the equilibrium conditions. The concentration ratio of products and reactants increases and levels of at the equilibrium, reaching a constant value called 'The equilibrium constant'

Ke = [C]/[A][B]

please click the animation controls