Question

Составьте ионно-молекулярные и молекулярные уравнения гидролиза солей Cs2CO3, NiCl2, NH4CH3COO, LiNO2. Какое значение рН (>7<) имеют растворы этих солей?

Answer 1

1).  Cs2CO3 + H2O = CsOH + CsHCO3

      2Cs(+) + CO3(2-) + H2O = Cs(+) + OH(-) + Cs(+) + HCO3(-)

      CO3(2-) + H2O =  OH(-) + HCO3(-)

 

  NiCl2 + H2O = Ni(OH)Cl + HCl   

  Ni(2+) + 2Cl(-) + H2O = NiOH(+) + 2Cl(-) + H(+)   

  Ni(2+) + H2O = NiOH(+) + H      

  

LiNO2 + H2O = LiOH + HNO2   

Li(+) + NO2(-) + H2O = Li(+) + HNO2 + OH(-) 

NO2(-) + H2O = HNO2 + OH(-)  

 

2) рН>7 среда щелочная

 

Answer 2

Ionno-molecular and molecular equations for the hydrolysis of salts Cs2CO3, NiCl2, NH4CH3COO, LiNO2

The hydrolysis of salts involves the reaction of water molecules with the ions present in the salt. This reaction can result in the formation of acidic or basic solutions, depending on the nature of the ions involved. Let's examine the hydrolysis of the salts Cs2CO3, NiCl2, NH4CH3COO, and LiNO2.

1. Cs2CO3 (Cesium Carbonate): - The ionno-molecular equation for the hydrolysis of Cs2CO3 can be written as: Cs2CO3 + 2H2O → 2CsOH + H2CO3 - The molecular equation for the hydrolysis of Cs2CO3 can be written as: Cs2CO3 + 2H2O → 2CsOH + CO2↑

2. NiCl2 (Nickel(II) Chloride): - The ionno-molecular equation for the hydrolysis of NiCl2 can be written as: NiCl2 + 2H2O → Ni(OH)2 + 2HCl - The molecular equation for the hydrolysis of NiCl2 can be written as: NiCl2 + 2H2O → Ni(OH)2↓ + 2HCl

3. NH4CH3COO (Ammonium Acetate): - The ionno-molecular equation for the hydrolysis of NH4CH3COO can be written as: NH4CH3COO + H2O ⇌ NH4OH + CH3COOH - The molecular equation for the hydrolysis of NH4CH3COO can be written as: NH4CH3COO + H2O ⇌ NH4OH + CH3COOH

4. LiNO2 (Lithium Nitrite): - The ionno-molecular equation for the hydrolysis of LiNO2 can be written as: LiNO2 + H2O → LiOH + HNO2 - The molecular equation for the hydrolysis of LiNO2 can be written as: LiNO2 + H2O → LiOH + HNO2

pH values of the solutions of these salts

The pH value of a solution depends on the concentration of hydrogen ions (H+) present in the solution. A pH value greater than 7 indicates that the solution is basic, while a pH value less than 7 indicates that the solution is acidic.

1. Cs2CO3 (Cesium Carbonate): - The hydrolysis of Cs2CO3 results in the formation of CsOH and H2CO3. Since CsOH is a strong base and H2CO3 is a weak acid, the resulting solution will be basic. Therefore, the pH of the solution will be greater than 7.

2. NiCl2 (Nickel(II) Chloride): - The hydrolysis of NiCl2 results in the formation of Ni(OH)2 and HCl. Since Ni(OH)2 is an amphoteric substance that can act as both a base and an acid, and HCl is a strong acid, the resulting solution will be acidic. Therefore, the pH of the solution will be less than 7.

3. NH4CH3COO (Ammonium Acetate): - The hydrolysis of NH4CH3COO results in the formation of NH4OH and CH3COOH. Since NH4OH is a weak base and CH3COOH is a weak acid, the resulting solution will be slightly acidic. Therefore, the pH of the solution will be less than 7.

4. LiNO2 (Lithium Nitrite): - The hydrolysis of LiNO2 results in the formation of LiOH and HNO2. Since LiOH is a strong base and HNO2 is a weak acid, the resulting solution will be basic. Therefore, the pH of the solution will be greater than 7.

Please note that the pH values mentioned here are approximate and can vary depending on the concentration of the salts and other factors.