Question

2. Which of salts hydrolyze in aqueous solution: (NH4)2CO3, FeS, NiCl2? Write ionic equations for the hydrolysis reactions, Predict the pH of the solution equal 7, greater than 7, less than 7).

Answer 1

Only ammonium carbonate and NiCl₂ undergo hydrolysis in aqueous solution.

FeS does not undergoes hydrolysis in aqueous solution.

The reactions involved in the hydrolysis of ammonium carbonate are

1) (NH₄)₂CO₃ (aq) --> 2NH⁴⁺ + CO₃²-

(2) NH⁴⁺ + H₂O(l) <--> NH₃(aq) + H₃O⁺

(3) CO₃^2- + H₂O(l) <--> HCO^3- + OH^-

The pH of this solution would be basic or alkaline (greater than 7).

The hydrolysis of NiCl₂ will occur as

NiCl2 + 2 H₂O  --> Ni(OH)₂ + 2 HCl

The pH of this solution would be acidic (less than 70).This is because the HCl produced is a strong acid. The pH of the resultinf solution will be around 4.i.e., acidic.