Get COMMON ION & BUFFER PROBLEMS KEY

Common Ion Effect in Buffer Solutions Due to Le Chatelier's Principle, the equilibrium will shift to favor the reactants (to the left). The pH increases because the ionization (and dissociation) of the acid is decreases.

A solution with more weak base, [A-], has a higher buffer capacity for addition of strong acid. Similarly, a buffer will break when the amount of strong base added is so large it consumes all the weak acid, through the reaction HA + OH- → A-+ H2O.

Answer and Explanation: The buffering capacity of a buffer system is at maximum when the pH is equal to the pK . This happens when the concentrations of the acid and base components of the buffer are equal or near equal.

A buffer works through a phenomenon called the common ion effect. The common ion effect occurs when a given ion is added to a mixture at equilibrium that already contains the given ion. When this happens, the equilibrium shifts away from forming more of that ion.

Buffer capacity depends on the amounts of the weak acid and its conjugate base that are in a buffer mixture. The more concentrated the buffer solution, the greater its buffer capacity.

The pKa of a buffer is commonly perceived as the pH of the said buffer when the concentrations of the two buffering species are equal, and where the maximum buffering capacity is achieved. However, it is often forgotten, that when defined as above, pKa depends on buffer concentration and temperature.

However, a good buffer is often selected based on the pKa (which measures acidic strength) or dissociation constant of the weak acid in a system. Factors such as temperature fluctuations and concentration can directly affect the pKa of a buffer solution. Chemical buffers exist naturally as part of biological systems.

Buffer capacity depends on the amounts of the weak acid and its conjugate base that are in a buffer mixture. The more concentrated the buffer solution, the greater its buffer capacity.