盐类水解（Salt hydrolysis）.docVIP

盐类水解（Salt hydrolysis） (a) hydrolysis of salts formula: weak to hydrolysis, weaker hydrolysis, weak double double hydrolysis, who is strong who was of. (1) weak hydrolysis Salt is required to have weak acids, root ions, or weak basic metal ions (including ammonium ions). Such as: NaCl in the Na+ corresponding to the base is strong alkali NaOH, then Na+ is a strong alkali metal ions, not hydrolysis. The Cl- in NaCl corresponds to a strong acid, HCl, and Cl- is a strong acid ion, and it does not hydrolyze. Therefore, NaCl does not hydrolyze in aqueous solution. Another example is that the CH3COO- in CH3COONa corresponds to weak acid CH3COOH, while CH3COO- is weak acid and the root ion will hydrolyze. Consumption of H2O ionized H+ is combined into CH3OOH molecules. Make the water OH- more. So, CH3COONas water solution is alkaline. (2) the weaker, the more hydrolysis The weaker the acidity of the acid or base of the ion in the salt or the weaker the basicity, the greater the degree of hydrolysis. Such as: Na2CO3 and Na2SO3 The CO3^2- corresponding to the acid is H2CO3; the SO3^2- corresponding to the acid is H2SO3 Because the acidity of H2CO3 is weaker than H2SO3 However, the degree of hydrolysis of CO3^2- is greater than the degree of hydrolysis of SO3^2-, and the binding of H+ is more. Therefore, the basicity of Na2CO3 is stronger than that of NaSO3. (3) double weak double hydrolysis When the base of the cation in the salt is weak, and the anion in the salt corresponds to a weak acid, the two ions of the salt are hydrolyzed. The OH- is ionized by cation hydrolysis bound water; ionized hydrolysis water combines with ionized water to ionize H+, so the degree of double hydrolysis is often greater. For example, the corresponding base of NH4+ in CH3COONH4 is weak base NH3*H2O; the corresponding acid of CH3COO- is weak acid CH3COOH Both NH4+ and CH3COO- hydrolyze, and NH4+ combines with OH- to form NH3*H2O; CH3COO- combines with H+ to form CH3COOH, which promotes each other,