Classification of reactions

• Homogeneous reaction = in gas phase
  • produces a gas-product
  • if the product is solid, then the reactions can have a deletorious effect to be avoided
    • big particles can be created in the gas-phase - clusters that fall and stick on substrate, which will result in poor morphology and properties
• Heterogeneous reaction = with formation of solid, takes place at the surface

The reaction rate (speed with which the reaction take place) for a reaction of the type : A + B = C + D, can be defined as:

• depends on partial pressure of gases (p_A, p_B), temperature (T) and the energy required for the reaction to take place (E_a)