Equilibrium + Acids/Bases

• Collision Theory


  For a reaction to occur, the reactants must have: sufficient energy (KE), proper arrangement, and collide.
• Factors that increase the rate of reaction


  • Temperature
  • Concentration
  • Catalyst
  • Pressure/Volume
  • Surface area
• Temperature increase


  Frequency of collisions increases because particles have more kinetic energy and move more quickly
• Concentration increase


  Frequency of collisions increases because there are more particles to collide with each other
• Catalyst


  Speeds up a reaction by lowering the activation energy and making it easier to occur
• Pressure increase (for gases)


  Frequency of collisions increases because the volume decreases and the particles are forced closer together
• Surface area increase


  Frequency of collisions increases because there is more area for collisions to occur, which leads to a faster rate of reaction
• Equilibrium


  Chemical equilibrium occurs when the rate of the forward reaction equals the rate of the reverse reaction. At equilibrium, the amount/concentration of reactants and products is CONSTANT. This is an example of dynamic equilibrium.
• Chemical reactions can only reach (full) equilibrium in a closed system. In an open system the amount of products/reactants can change, the system must reestablish equilibrium.
• Types of Equilibrium


  • Solution Equilibrium
  • Phase Equilibrium
• Solution Equilibrium


  In a saturated solution the rate of dissolving = rate of crystallization
• Phase Equilibrium


  Rate of evaporation = rate of condensation, Rate of freezing = rate of melting, Rate sublimation = rate of deposition
• Le Chatelier's Principle


  A system at equilibrium will respond to relieve any stress by increasing forward or reverse reaction to re-establish equilibrium.
• Types of stress


  • Change in concentration
  • Change in temperature
  • Change in pressure (for gas)
• AATT


  Add Away Take Toward
• Temperature increase


  Equilibrium will shift toward the endothermic reaction (side with no heat)
• Temperature decrease


  Equilibrium will shift toward the exothermic reaction (side with heat)
• Pressure increase


  Equilibrium will shift toward the side with fewer moles of gas
• Pressure decrease


  Equilibrium will shift toward the side with more moles of gas
• Electrolytes


  Ionic compounds that produce mobile ions when they are added to a solution. The movement of charged particles allows it to conduct electricity.
• All acids and bases are electrolytes
• Molarity

  The greater the molarity, the better it is at conducting electricity
• Arrhenius theory


  Acids and bases differ based on what ions are released in aqueous solutions. Acid release H+ in solution, Base release OH- in solution.
• H+ ions will not actually exist in an aqueous solution (water) because H+ is a proton with no electrons. It wants to have 2 valence electrons and will form a bond with H2O to get 2 electrons. (Thus H3O+)
• Table K and L shows you common acids and bases.
• Bronsted theory


  Acids and bases differ based on how they interact with H+. Acid is a H+ (proton) donor, Base is a H+ (proton) acceptor.
• BAAD


  Base Accepts Acid Donates
• Conjugate Acid and Base Pairs

  Two compounds/species related by the loss of an H+/proton. Bronsted acid donates a proton and becomes a conjugate base, Bronsted base accepts a proton and becomes a conjugate acid.
• Diprotic Acid

  An acid that can donate two protons (H+)
• Amphoteric


  Compound that can act as both an acid and a base
• The dissociation of water will always produce equal amounts of H3O+ and OH- so it won't be acidic or basic. [H3O+] = [OH-] neutral
• pH Scale


  Measures the H+ or OH- concentration in a solution, [H+] or [OH-]. Goes from 0 - 14. Less than 7 is acidic, greater than 7 is basic. 7 is neutral. pH scale is logarithmic, grows quickly by power of 10.
• Acidic solutions


  The concentration of H+ is greater than the concentration of OH-
• Basic solutions


  The concentration of H+ is less than the concentration of OH-
• Calculating pH


  1. pH = -log[H+] → 10-pH = [H+]

  2. pOH = -log[OH-]

  3. pH + pOH = 14
• Indicators


  It tells you the pH range where a color change is occurring. This color change is between the two colors listed in the right hand column of the table. The color change that will occur between the listed pH is a mix of the two given colors (in between red and yellow is green).
• Neutralization and Titration


  1. Acid + Base → Salt + H2O

  2. In neutralization reactions the amount of H+ is equal to the amount of OH-. Either the concentration of H+ is equal to the concentration of OH- or the number of moles of H+ is equal to the number of moles of OH-. It is a double replacement reaction.

  3. Titration - a lab process where you figure out the unknown concentration of an acid or base used in a neutralization reaction

  4. MaVa = MbVb

  5. The question is only true if the ratio of acid to base is 1:1

  6. If the ratio of acid to base is not 1:1 then you divide that side of the equation by the coefficient. (after you balance the equation)

  7. In a titration the point when the acid neutralizes the base is when moles of H+ is equal to moles of OH- this is also called the endpoint or equivalence point.