Equilibrium Question 909
Question: Arrange the following in increasing order of $ pHKNO_3(aq),,CH_3COON(aq), $
$ NH_4Cl(aq),,C_6H_5COONH_4(aq) $
Options:
A) $ CH_3COONa<C_6H_5COONH_4 $ $ <NH_4Cl<KNO_3 $
B) $ KNO_3<NH_4C<CH_3COONa $ $ <C_6H_5COONa $
C) $ NH_4Cl<KNO_3<CH_3COONa $ $ <C_6H_5COONH_4 $
D) $ NH_4Cl<KNO_3<C_6H_5COONH_4 $ $ <CH_3COONa $
Show Answer
Answer:
Correct Answer: D
Solution:
(i) $ KNO_3 $ is a salt of strong acid and strong base, hence its aqueous solution is neutral; pH = 7
(ii) $ CH_3COONa $ is a salt of weak acid and strong base/hence, its aqueous solution is basic ; pH > 7
(iii) $ NH_4Cl $ is a salt of strong acid and weak base, hence its aqueous solution is acidic; pH < 7
(iv) $ C_6H_5COONH_4 $ is a salt of weak acid, $ C_6H_5COOH $ and weak base, $ NH_4OH $ . But $ NH_4OH $ is slightly stronger than $ C_6H_5COOH $ . Hence, pH is slightly > 7.
Therefore, increasing order of pH of the given salts is $ <CH_3COONa $
