Answer:
AI(NO₃)₃ → Acidic pH < 7
CH₃NH₃CN → Neutral pH = 7
NaCIO → Basic pH > 7
CH₃NH₃CI → Acidic pH < 7
NaNO₃ → Neutral pH = 7
Explanation:
First of all we dissociate the salts:
Nitrate anion comes from the nitric acid which is strong, so the anion is the conjugate weak base. It does not react to water, but the Al is an special case. Aluminum as a cathion comes from the Al(OH)₃ which is a base but this compound can also react as an acid, it is called amphoterous.
Al³⁺ + H₂O ⇄ Al(OH)²⁺ + H⁺
Aluminium cathion reacts to water in order to produce a complex and to give protons to the medium, so the salt is acid.
Both ions come from a weak base and a strong acid, so both ions are the conjugate strong base and acid, respectively. They can make hydrolysis to water so the salt is neutral.
CH₃NH₃⁺ + H₂O ⇄ CH₃NH₂ + H₃O⁺ Ka
CN⁻ + H₂O ⇄ HCN + OH⁻ Kb
Sodium cathion, comes from the strong base NaOH so it is does not react to water. It is the conjugate weak acid. Hypochlorite comes from the weak acid, so it can hydrolyse to water.
ClO⁻ + H₂O ⇄ HClO + OH⁻ Kb
Hypochlorous acid is formed giving OH⁻ to medium, so the salt is basic.
Chloride comes from the strong acid HCl. It does not react to water.
Methylammonium comes from the weak base, methylamine so it can react to water in order to make hydrolysis. The salt will be acidic.
CH₃NH₃⁺ + H₂O ⇄ CH₃NH₂ + H₃O⁺ Ka
NaNO₃ → Na⁺ + NO₃⁻
Both ions come from a strong base and acid, so they are the conjugate base and acid, respectively. As they do not make hydrolisis in water, the salt will be neutral.
