Welcome to the Chemistry II Website

Chapter 17

  • Chemical Kinetics: branch of chemistry that deals with rates of reactions and mechanisms of chemical reactions.

  • Thermodynamics: study of the changes in energy in chemical reactions, the influence of temperature on those changes, and the other factors that allow/cause chemical reactions to take place.

  • Collision Theory: states that particles must collide in order for chemical change to take place. (these particles may be ions, atoms, or molecules)

  • There are four main factors that affect the rate of a chemical reaction:

  • Heat Content and Enthalpy

  • Since energy must be added to ice to change it to the liquid phase, then:

  • delta H = HH2O(l) - HH2O(s)
    Heat of Fusion
    reactants vs. products

    Heat of Formation

              Exothermic Reactions          vs.          Endothermic Reactions
              *energy is a product                       *energy as a reactant
    *large neg. values give *small neg. or pos. values-- off a lot of energy during unstable (explosives) its formation--very stable

    Calculating heat of formation:
    1 mole of ethyl alcohol is -9.5 x 102 kJ or -950 kJ. How much heat is produced when 11.5 grams of ethyl alcohol is burned?
            C2H5OH    x    1 mol  =  0.25 mol
                          46.08 g
           0.25 mol C2H5OH   x   -950 kJ  =  -237.09 kJ
                                  1 mol

    Hess's Law of Constant Heat Summation
    Method 2 for calculating heat of formation:
    Heat of formation of the reaction = heat of formation of the products - heat of formation of the reactants