What would happen to a weak base dissociation equilibrium if more products were added?

1 Answer
Feb 19, 2017

Answer:

Just like any equilibrium reaction, when more products are added, Le Chatelier's principle tells us that the position of equilibrium shifts in the direction of the reverse reaction.

Explanation:

I will write the following generic dissociation of a weak base B, to help me explain:

#H_2O+B rightleftharpoons HB+OH^-#

Adding more of the product #HB# to this equilibrium will cause a shift to the left, resulting in a new equiibrium having a higher concentration of both #H_2O# and #B#, a higher concentration of #HB# (because the shift the Le Chatelier refers to is generally one which partially consumes the added material) and a lower concentration of #OH^-#.

Since the #[OH^-]# has been reduced, the solution is now less basic that it was before #HB# was added. The pH has decreased.