ZnCl2 (zinc chloride) is a salt that is soluble in water. When dissolved in water, it dissociates into its constituent ions: Zn2+ and 2Cl-. Dilute HCl is a solution of hydrogen chloride (HCl) in water. When HCl is dissolved in water, it also dissociates into its constituent ions: H+ and Cl-.

ZnCl2 does not react with dilute HCl because the two solutions contain the same ions. Zn2+ and Cl- ions from ZnCl2 and H+ and Cl- ions from HCl will not react with each other. Therefore, no reaction will take place between ZnCl2 and dilute HCl.