Acids and Bases

• Spontaneous Reaction – reaction that occurs on its own without intervention of an external force
• Non-Spontaneous Reaction – reaction that occurs in the presence of an outside intervention
• Entropy (S) - is the thermodynamic quantity of randomness or disorder of particles atoms, molecules or ions.
• Standard Entropy (Sº) - is the absolute entropy of 1 mole of a substance at standard conditions (1atm and 25ºC).
• Gas - contains highest entropy
• Solid - contains lowest entropy
• Exothermic Processes - processes where heat energy is released from the system to surroundings.
• Liquid - has higher entropy than solid but lower than gas
• Endothermic Processes - processes where heat energy is absorbed by the system from its surroundings.
• diamond has a lower entropy than graphite due to greater order of carbons
• molecules with greater number of atoms have greater entropies as a result of greater number of molecular motions
• Gas - has highest entropy because it can move freely in all directions, giving maximum disorder
• bigger atoms have greater entropies than smaller atoms for having smaller spacing between energy levels.
• Increase in Temperature = Increase in Entropy
•   Endothermic Phase Changes (fusion, evaporation, sublimation) above melting/boiling/sublimation temperature
• Exothermic Phase Changes (freezing, condensation, deposition) below freezing/condensation/deposition temperature
• Entropy of Reaction (ΔS) - is the change in entropy from the initial state to the final state of a reaction or a process
• Volume Changes

  A) spontaneous

  B) nonspontaneous

  C) more disordered

  D) less disordered

  
• Entropy Change of the Universe - The sum of entropies of the system and surroundings
• Second Law of Thermodynamics - In an isolated system, the entropy of the universe for a spontaneous change is increasing
• Second Law of Thermodynamics - this law is consistent with the natural tendency for reactions to proceed with maximum entropy
• Entropy Change by Surroundings - the heat released by the system is absorbed by the surroundings
• Third Law of Thermodynamics - the entropy of a highly crystalline substance at the absolute zero
• Gibbs Free Energy - Also known as Gibbs energy, is the energy available for a process to do at work
• ΔG < 0 - reaction is spontaneous in forward direction
• ΔG > 0 - reaction is spontaneous in backward direction
• ΔG = 0 - reaction is spontaneous in both direction
• Acid - can change the color of litmus from blue to red
• Bases - Can change the color of litmus from red to blue
• Acid - substance that produces protons (H+) or Hydronium ions (H30+)
• Base – releases hydroxide ions (OH-)
• Acid – Proton Donor
• Base – Proton Acceptor
• Autoionization of water – water can undergo an acid-base reaction with itself to produce hydronium (or hydrogen) and hydroxide ions.
• pH Meter - measures difference in the electric potential (or voltage) created in the presence of hydrogen ion.
• pH – is a measure of hydrogen ion content in an aqueous solution. It is equal to the negative logarithm of hydrogen ion concentration (in mol/L) to the base 10:
• Neutral - H+ = OH-
• Acidic - H+ > OH-
• Basic - H+ < OH-
• zero - entropy change of the universe for a reversible reaction