Question

Measure pH

NaHCO3 = 8.56

Na2CO3= 11.14

NH4Cl = 5.85

[Al(H2O)6]Cl3 = 3.50

Write down the hydrolysis reactions for the each of the salts. Dissociate the salt into its cation and anion and ignore the inert species. Make sure that the reaction is consistent with the measured pH.

1. NaHCO3

2. Na2CO3

3. NH4Cl

4. [Al(H2O)6 ]Cl3

Answer 1

1. Hydrolysis of NaHCO₃ produces a strong base and a weak acid which is as follows

Formula equation: NaHCO₃ + H₂O = NaOH + H₂CO₃

strong base weak acid

Net ioinc equation: HCO₃^- + H₂O = H₂CO₃ + OH^-

Since the hydrolyis of NaHCO₃ produces an aqueous solution which is weakly basic in nature, so the measued value of pH =8

3. Hydrolysis of NH₄Cl produces a weak base and a strong acid which is as follows

Formula equation: NH₄Cl + H₂O = NH₄OH + HCl

weak base strong acid

Net ioinc equation: NH₄ ⁺ + H₂O = NH₄OH + H⁺

Since the hydrolyis of NH₄Cl produces an aqueous solution which is weakly acidic in nature, so the measued value of pH = 5.85

2. Hydrolysis of 1 mole of Na₂CO₃ produces 2 moles of strong base and one mole of wak acid which is as follows

Formula equation: Na₂CO₃ + 2H₂O = 2 NaOH + H₂CO₃

strong base weak acid

Net ioinc equation: CO₃ ^2-  + 2H₂O = H₂CO₃ + 2OH^-

Since the hydrolyis of NaHCO₃ produces an aqueous solution which is strongly basic in nature,  so the measued value of pH =11.14

4. Hydrolysis of Al(H₂O)₆Cl₃ produces a strong acid which is as follows

equation: Al(H₂O)₆Cl₃ + H₂O = Al(H₂O)₆(OH)Cl₂ + HCl

   strong acid

Since the hydrolyis of Al(H₂O)₆Cl₃  produces an aqueous solution which is acidic in nature,

so the measued value of pH = 3.5