Question

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

Answer 1

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.