Question

6. (2 points) Determine whether each of the following salts are acidic, basic, or neutral. a. Na SO. b. CHÚNHOI(Kh of CH3NH2 = 4.4 x 10"; K, of HOI = 2.3 x 10'') c. KOB d. CsHsNHNO;

Answer 1

6

a. Sodium Sulphate (Na₂SO₄) is a neutral salt.When dissolved in water , solution  pH is 7 ; since it is derived from a strong acid (sulfuric acid) and a strong base (sodium hydroxide).

Na₂SO₄ + H₂O $\rightarrow$ 2 Na⁺ (aq) + SO₄^2-(aq) + H₂O

b. CH₃NH₃OI is derived from weak base and very weak acid.

CH₃NH₂ + HOI   $\rightarrow$ CH₃NH₃^+-OI

In water,    CH₃NH₃⁺   + H₂O $\rightleftharpoons$  CH₃NH₂ + H₃O⁺

^-OI  + H₂O $\rightleftharpoons$   HOI + OH^-

nature of this salt will depend on Ka and Kb values.

Since, Kb >> Ka :  solution will be basic in nature as acid is weaker than base and pH value will be more than 7.

c. KOBr is salt from strong base (KOH) and weaker acid (HOBr).The solution of such a salt is basic in nature. Anion of salt reacts with water to form  weak acid and OH^- ions.

^-OBr + H₂O $\rightleftharpoons$   HOBr + OH^-    (pH > 7 )

d. C₅H₅NHNO₃ , is salt from strong acid (HNO₃) and weaker base (Pyridine, C₅H₅N ).The solution of such a salt is acidic in nature. Cation of salt reacts with water to form  weak base and H⁺ ions.

C₅H₅NH⁺ + H₂O $\rightleftharpoons$   C₅H₅N + H₃O⁺    (pH < 7 )