What is the function of a buffer?

Question

Olivia Anton · Accepted Answer

To maintain the #pH# of a solution around a given value.....

And a buffer thus acts to RESIST gross changes in #pH#. Since a weak acid and its conjugate base are usually present in APPRECIABLE concentrations in a buffer, the following equilibrium can be used to describe the behavior of the acid-base pair: #HA(aq) +H_2O(l)rightleftharpoonsH_3O^+ + A^-# And as usual, the equilibrium equation can be used to illustrate this. #K_a=([H_3O^+][A^-])/([HA(aq)])#, and #K_a# is typically measured and defined under standard conditions of #298*K# and near one atmosphere. And as for any equation, we can manipulate the equation by dividing, multiplying, adding to, subtracting from, provided that we do the SAME thing to BOTH sides of the equality. One thing we can do is to take #log_10# of BOTH sides...... And thus. #log_10K_a=log_10[H_3O^+]+log_10{[[A^-]]/([HA(aq)]}}# Regarding reorganization...... #underbrace(-log_10[H_3O^+])_(pH)=underbrace(-log_10K_a)_(pK_a)+log_10{[[A^-]]/([HA(aq)]}}# And thus....#pH=pK_a+log_10{[[A^-]]/[[HA]]}# This is a form of the buffer equation, which you will have to be able to use effectively. And this says that when #[A^-]-=[HA]#, #pH=pK_a# because #log_10{[[A^-]]/[[HA]]}=log_10(1)=0#. And thus addition of LESS than stoichiometric quantities of acid or base to the solution, does not dramatically alter solution #pH#.... Biological systems are extensively buffered.

Mateo Aguilar · Answer

undefined The function of a buffer is to resist changes in pH when an acid or base is added to a solution. Buffers are composed of a weak acid and its conjugate base, or a weak base and its conjugate acid. They maintain the pH of a solution within a relatively narrow range by neutralizing the added acid or base without significant changes in pH.