General Chemistry 2

• Thermochemistry


  Is concerned with heat changes that occur during chemical reactions.
• Thermodynamics


  Is the science of the relationship between heat and other forms of energy.
• A reaction that does occur under the given set of conditions is called a spontaneous reaction.
• If a reaction does not occur under specified conditions, it is said to be non-spontaneous.
• Spontaneous Processes


  Are those that can proceed without any outside intervention.
• Processes that are spontaneous in one direction are non-spontaneous in the reverse direction.
• Entropy (S) is a term coined by Rudolf Clausius in the 19th century.
• Entropy can be thought of as a measure of the randomness or disorder of a system.
• Entropy Formula:


  ∆s=s°final-s°initial
• 2ND LAW OF THERMODYNAMICS


  States that the states of entropy of the entire universe, as an isolated system, will always increase over time.
• 2ND LAW OF THERMODYNAMICS


  It also states that the changes in the entropy in the universe can never be negative.
• 4 Processes but led to an increase in entropy of the system:

  1. Melting
  2. Vaporization
  3. Dissolving
  4. Heating
• 4 Processes but led to an increase in entropy of the system:


  1. Melting
  2. Vaporization
  3. Dissolving
  4. Heating
• Entropy is positive when it under went melting, evaporation, and sublimation.
• If a reaction produces more gas molecules than it consumes, ∆S° is positive.
• If there is no net change in the total number of gas molecules, then ∆S° may be (+) or (-) but will be relatively small numerically.
• Entropy is negative when it under when deposition, solidification, and condensation.
• If the total number of gas molecules diminishes, ∆S° is negative.
• Entropy and Enthalpy can be calculated from the table of standard values.
• Entropy Formula


  ∆s°rxn=Σns°(product)-Σms°(reactants)
• Gibbs Free Energy (G)
• Gibbs Free Energy (G)


  Another thermodynamic property that is used to predict whether the reaction or process will be spontaneous or non-spontaneous.
• Gibbs free energy is defined as G=H-TS.
• The change in free energy ∆G of a system for a constant temperature process is:

  ∆G=∆H-T×∆S
• ∆G<0


  (Condition in terms of ∆G) The reaction is spontaneous in the forward direction.
• ∆G>0

  (Condition in terms of ∆G) The reaction is non-spontaneous. The reaction is spontaneous in the backward direction.
• ∆G=0


  (Condition in terms of ∆G) The system is at equilibrium. There is no net change.
• 3 Conditions for spontaneity and equilibrium at constant temperature and pressure in terms of ∆G:

  1. ∆G<0
  2. ∆G>0
  3. ∆G=0
• 3 Conditions for spontaneity and equilibrium at constant temperature and pressure in terms of ∆G:


  1. ∆G<0
  2. ∆G>0
  3. ∆G=0
• ⇌


  Reversible Symbol
• Chemical Equilibrium


  A condition in the course of a reversible chemical reaction in which no net change in the amount of reactants and products occurs.
• Chemical Equilibrium


  aA+bB⇌cC+dD
• La Chatelier's Principle


  This principle states that when factors that influence an equilibrium are altered, the equilibrium will shift to a new position that tends to minimize those changes.
• La Chatelier's Principle


  States that when a system experiences a disturbance, it will respond to restore a new equilibrium states.
• 3 disturbance.


  Concentration, Pressure, and Temperature.
• (Change in Concentration) If additional reactant is added to a system, the equilibrium will ship to the right, towards the products, more reactants lead to the formation of more products.
• (Change in Concentration) If the concentration of the product will be reduced or decreased, the equilibrium will also ship to the right, formation of products is needed to achieve equilibrium.
• (Change in Concentration) If additional product is added to a system, equilibrium will shift to the reactant side (to the left), more reactants must be produced.
• (Change in Concentration) If reactants will be removed from a system, equilibrium will also ship to the left.
• (Change in Pressure) An increasing pressure will cause the reaction to go toward the direction that favors the formation of a smaller volume.