Acid-Base Equilibria


acid-base indicator

weak acid or base that is different colors in the dissociated and nondissociated states


solution that that resists a change in pH when acid or base is added and contains significant quantities of a weak acid and its conjugate base or a weak base and its conjugate acid

buffer capacity

number of moles of strong acid, protons (H+), or strong base, hydroxide ions (OH), that can be added to one liter of solution before the pH changes by 1 in either direction

buffer range

pH range over which a buffer is effective in stabilizing the pH of a solution; The effective range of a buffer is within one pH unit above and below the pH of the buffer.

diprotic acid

acid that can donate two protons to solution

end point

pH at which an acid-base indicator changes color

equivalence point

point at which all the acid or base molecules in an acidic or basic solution have been neutralized

Le Chatelier's principle

principle that states that a change in the temperature, pressure, or concentration of a component will cause the equilibrium condition of a chemical system to change in a way that reduces the change


ionic compound produced by a neutralization reaction of an acid and a base

stepwise ionization

process by which a diprotic acid or a triprotic acid ionizes by losing one proton at a time. Each ionization has a unique equilibrium constant.


quantitative method that relies on measuring the volume of a solution of a known concentration necessary to neutralize a given volume of acid or base

titration curve

graph showing the change in pH of an analyte solution as titrant is added

triprotic acid

acid that can donate three protons to solution