Why would you be advised to add hydrochloric acid dropwise, rather than in one go?
Do you ask in the context of a titration......?
Now you do have the order of addition right; you always add acid to water, and never the reverse. If you ask why we perform a titration dropwise, then clearly it is because we wish to determine the stoichiometric end point precisely. Moreover, when we do a titration, we typically deal with concentrations that are
When a concentrated acid is added to water, say
Dropwise addition can thus moderate the evolution of heat.