Final answer:
Reactions between a strong acid (SA) and a weak base (WB), or a strong base (SB) and a weak acid (WA) will not always go to completion.
Step-by-step explanation:
The statement that reactions between a strong acid (SA) and a weak base (WB), or a strong base (SB) and a weak acid (WA) will always go to completion is false.
In these reactions, the strong acid or strong base will completely dissociate into ions in water, while the weak base or weak acid will only partially dissociate. As a result, there will be a small amount of undissociated weak base or weak acid remaining in the solution, which means the reaction is not going to completion.
For example, in the reaction between hydrochloric acid (a strong acid) and ammonia (a weak base), only the hydrochloric acid will completely dissociate into H+ and Cl- ions, while ammonia will only partially dissociate into NH4+ and OH- ions. As a result, there will be a small amount of undissociated ammonia remaining in the solution.