# Why would you be advised to add hydrochloric acid dropwise, rather than in one go?

Aug 2, 2017

Do you ask in the context of a titration......?

#### Explanation:

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 $0.1 - 0.5 \cdot m o l \cdot {L}^{-} 1$ in strength; these are fairly dilute solutions.

When a concentrated acid is added to water, say $H C l$ or ${H}_{2} S {O}_{4}$, the solution will heat up as the hydronium ions are solvated....i.e.

$H X \left(a q\right) + {H}_{2} O \left(l\right) \rightarrow {H}_{3} {O}^{+} + {X}^{-} + \Delta$

Dropwise addition can thus moderate the evolution of heat.