Question

You dissolve NH&CN in water. Will the resulting solution be acidic or basic? You need to explain your answer using the appropriate Ka and Kb values. OR you can show your calculations!

Answer 1

NH₄CN is a salt formed from weak base NH₄OH and weak acid HCN so that it undergoes complete hydrolysis

Further explanation

The hydrolysis process is a term used for the reaction of substances with water

There are 3 types of hydrolysis salts

1.Salt from strong acids and strong bases does not undergo hydrolysis so that the pH of the neutral solution = 7

2.Salt from strong acids and weak bases (pH <7) or from strong bases and weak acids (pH> 7) will be partially / partially hydrolyzed

3.Salt from weak acids and weak bases (pH depends on the value of Ka and Kb) will be completely hydrolyzed

NH₄CN is a salt formed from weak base NH₄OH and weak acid HCN so that it undergoes complete hydrolysis

NH₄OH + HCN⇒NH₄CN+H₂O

Can be formulated :

$\tt [H^+]=\sqrt{\dfrac{Kw\times Ka}{Kb} }$

Ka> Kb then [H +]> 7 and pH <7 ⇒ acidic

Ka <Kb then [H +] <7 or pH> 7 ⇒alkaline

Ka = Kb then pH = 7 ⇒neutral