Question

Which acid-base chemical reaction is irreversible

strong acid added to water
weak base added to water
water on its own
weak acid added to water

Answer 1

Among the options provided, the reaction that is considered irreversible is "strong acid added to water." When a strong acid is dissolved in water, it completely dissociates into its ions, and this process goes to completion. For example, when hydrochloric acid (HCl) is added to water, it fully dissociates into hydrogen ions (H⁺) and chloride ions (Cl⁻), and this reaction cannot easily revert back to the original acid in the absence of the water.

In contrast, weak acids and weak bases do not fully dissociate in water, and thus their reactions can be reversible to some extent. Water on its own does not involve a significant acid-base reaction.