A weak acid would have a higher pH value than a strong acid at the same concentration. Strong acids dissociate completely in water, releasing more hydrogen ions (H\(^+\) and thus having a lower pH (more acidic). Weak acids only partially dissociate, resulting in fewer H\(^+\) ions and a higher pH (less acidic).

HCl is a strong acid because it dissociates completely when dissolved in water, thereby releasing more hydrogen ions and thus having a lower pH value when compared to ethanoic acid, a weak acid which dissociates partially when dissolved in water, thereby releasing less hydrogen ions, invariably having a higher pH, regardless of the fact that both acids have the same concentration of 0.5M.