buffer

• chemical equilibrium are affected by = TEMPERATURE, CONCENTRATION, PRESSURE

  • based on Le Chatelier's Principle
• BUFFERED SOLUTION

  • small changes pH level = small amount of strong acid or base added
• UNBUFFERED SOLUTION

  • no buffering solution = pH changes to small amounts of strong acid or base added
• BUFFER SOLUTION - TEMPERATURE

  • dissociation constant changes with temperature = concentration of ion changes
  • K = [HA] [OH-] / [A-]
  • K = constant value
  • [OH-] increase = [HA] & [A-] must change
• BUFFER SOLUTION - TEMPERATURE

  • K is small = buffering effect is small ; no HA enough in the solution
  • K increases = buffering effect is stronger at high temp
  • K decreases = buffering effect is weaker when warm or low temp
• pH = pKa + log ( [A-] / [HA]) - Henderson - Hasselbalch equation

  • [HA] - concentration of acid
  • [A-] - concentration of conjugate base
  • pH - concentration of [H+]
  • pKa - dissociation constant
• EFFECTIVE BUFFER = amount of acid & conjugate base are EQUAL