Flashcards in Acids, Bases, and Buffers Deck (11):
Law of Mass Action
Rate of rxn is partially determined by concentrations of reactants and products in addition to the equilibrium constant.
If product or reactant concentrations greatly increase, the rxn will move in other direction
Concentration of H+ in solution, measured -log[H]. Given that Keq of water is 1.8*10^-16, [H][OH]=1*10^-14 so pH + pOH =14
This is the acid dissociation constant, gives the strength of the acid, lower pKa means less acid is bound at equilibrium so the acid is stronger.
Henderson Hasselbach Equation
So pH=pKa at 50% dissociation
Bicarbonate Buffer System H-H equation
Bicarb buffer system regulates physiologic pH by taking up extra protons or hydroxyls without drastically changing the pH. This is an open system helped by CO2 exchange and bicarbonate excretion.
Normal Blood pH
Normal Bicarbonate Concentration
Why do weak acids make good buffers? What is maximal pH range for buffers?
Weak acids are good buffers because they are only partially associated at physiologic pH, meaning there is undissociated acid and conjugate base to take up extra H or OH.
Buffers work best within 1 pH (0.1 to 10 [A-]/[HA]) of pKa because acid is 50% dissociated when pH=pKa
Acid Base Problems