A sample of solid ammonia chloride NH4Cl, is dissolved in water...the solution found is acidic...explain why the solution is acidic?
Note the correct name is ammonium chloride. It is acid because the ammonium ion (the NH4^+) is hydrolyzed as follows:
NH4^+ + H2O ==> H3O^+ + NH3
The hydronium ion makes it acidic.
To understand why the solution is acidic, we need to look at the behavior of ammonia chloride (NH4Cl) when it dissolves in water.
When NH4Cl is dissolved in water, it dissociates into its constituent ions: NH4+ (ammonium) and Cl- (chloride). The NH4+ ion has the potential to release a hydrogen ion (H+) in water, which makes the solution acidic.
The acidity in this case is due to the acidic nature of the ammonium ion (NH4+). NH4+ can act as a weak acid by donating a proton (H+) to water, creating a hydronium ion (H3O+). The equilibrium reaction can be represented as follows:
NH4+ (aq) + H2O (l) ⇌ NH3 (aq) + H3O+ (aq)
In this equilibrium, the direction of the reaction depends on the concentration of H3O+ ions. Since the ammonium ion can release H+, it acts as a weak acid, leading to an excess of H3O+ ions in the solution and making it acidic.
As a result, when NH4Cl dissolves in water, the solution becomes acidic due to the presence of hydronium ions formed from the dissociation of NH4+ ions.