Examkin

Question

Difficulty: EasySalt Hydrolysis and Solution Acidity/Alkalinity

Match each aqueous salt solution to its characteristic effect on litmus paper at 25∘C25^\circ\text{C}.

  • Ammonium chloride solution (NH4Cl(aq)NH_4Cl(aq))Turns blue litmus paper red (pH<7pH < 7)
  • Sodium ethanoate solution (CH3COONa(aq)CH_3COONa(aq))Turns red litmus paper blue (pH>7pH > 7)
  • Sodium chloride solution (NaCl(aq)NaCl(aq))Has no effect on either red or blue litmus paper (pH=7pH = 7)

Answer

Ammonium chloride solution (NH4Cl(aq)NH_4Cl(aq)) matches with 'Turns blue litmus paper red (pH<7pH < 7)'; Sodium ethanoate solution (CH3COONa(aq)CH_3COONa(aq)) matches with 'Turns red litmus paper blue (pH>7pH > 7)'; Sodium chloride solution (NaCl(aq)NaCl(aq)) matches with 'Has no effect on either red or blue litmus paper (pH=7pH = 7)'.
Salt hydrolysis determines the acidity or alkalinity of an aqueous salt solution based on the strengths of the parent acid and base. Ammonium chloride (NH4ClNH_4Cl) yields acidic solutions (pH<7pH < 7) turning blue litmus red due to NH4+NH_4^+ cation hydrolysis. Sodium ethanoate (CH3COONaCH_3COONa) produces alkaline solutions (pH>7pH > 7) turning red litmus blue due to CH3COO−CH_3COO^- anion hydrolysis. Sodium chloride (NaClNaCl) consists of spectator ions from a strong acid and strong base, undergoing no hydrolysis and remaining neutral (pH=7pH = 7).

Step-by-Step Solution

1
Analyze the parent acid and base for Ammonium chloride (NH4ClNH_4Cl).
NH4ClNH_4Cl forms from HClHCl (strong acid) and NH3NH_3 (weak base). Cation hydrolysis occurs: NH4+(aq)+H2O(l)⇌NH3(aq)+H3O+(aq)NH_4^+(aq) + H_2O(l) \rightleftharpoons NH_3(aq) + H_3O^+(aq). Excess H3O+H_3O^+ turns blue litmus red.
Salts of strong acids and weak bases yield acidic solutions.
2
Analyze the parent acid and base for Sodium ethanoate (CH3COONaCH_3COONa).
CH3COONaCH_3COONa forms from CH3COOHCH_3COOH (weak acid) and NaOHNaOH (strong base). Anion hydrolysis occurs: CH3COO−(aq)+H2O(l)⇌CH3COOH(aq)+OH−(aq)CH_3COO^-(aq) + H_2O(l) \rightleftharpoons CH_3COOH(aq) + OH^-(aq). Excess OH−OH^- turns red litmus blue.
Salts of weak acids and strong bases yield alkaline solutions.
3
Analyze the parent acid and base for Sodium chloride (NaClNaCl).
NaClNaCl forms from HClHCl (strong acid) and NaOHNaOH (strong base). Neither ion undergoes hydrolysis. The solution remains neutral (pH=7pH = 7) and does not change litmus color.
Salts of strong acids and strong bases do not undergo hydrolysis.

Key Concept

Salt Hydrolysis and Solution Acidity/Alkalinity
Estimated Time:45s
Rate this question

Topics

Salt Hydrolysis and Solution Acidity/Alkalinity

More questions from this topic