# What is the pH for a 0.020*mol*L^-1 solution of HCl(aq)?

$p H = 1.70$
$p H = - {\log}_{10} \left[{H}_{3} {O}^{+}\right]$
$=$ $- {\log}_{10} \left(0.02\right)$, given that we assume hydrochloric acid dissociates completely to give stoichiometric ${H}_{3} {O}^{+} \left(a q\right)$:
$H C l \left(a q\right) + {H}_{2} O \left(l\right) r i g h t \le f t h a r p \infty n s {H}_{3} {O}^{+} + C {l}^{-}$