最新2-水化学成分和水化学指标
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– The relative amounts of an ion and its hydrolysis products will depend on the initial pH of the solution and the equilibrium constants describing the hydrolysis reactions.
• Al3+ + H2O −→ AlOH2+ + H+ • Al3+ + 2H2O −→ Al(OH)2+ + 2H+ • Al3+ + 3H2O −→ Al(OH)30 + 3H+ • Al3+ + 4H2O −→ Al(OH)4− + 4H+
Ion Hydrolysis
– In the case of the pH increase associated with the addition of Na2CO3 to water, it is the CO32− ion that hydrolyzes. For CO32−, only two hydrolysis products form:
– Anion hydrolysis thus results in an increase in the solution pH.
Ion Hydrolysis
– Monovalent ions are so weakly charged that they rarely hydrolyze. For example, NaCl is considered a neutral salt, i.e., producing no effect on pH when it is added to water.
Ion Hydrolysis
– The addition of AlCl3 or Na2CO3 to water, however, causes a marked change in the pH of water. In the case of AlCl3, it is the Al3+ ion that hydrolyzes and several hydrolysis products form representing Al3+ ions that have lost one, two, three and four hydrogen ions from their hydration sheaths.
Ion Hydrolysis
Ion Hydrolysis
– Would the cation tend to repel and perhaps eject a hydrogen ion into the bulk solution?
– Certainly one would think so and the tendency would be greater the higher the charge on the caBaidu Nhomakorabeaions. The process of hydrogen ion detachment from hydration sheaths and their ejection into the bulk solution is called hydrolysis.
– Hydrolysis is a reaction that accompanies ion hydration. Hydrogen ions are labile and can transfer from one water molecule to the next in solution. Imagine the hydrogen ions associated with the first neighbor water molecules around a monovalent cation in solution.
– This is because the field strengths (charge/surface area ratios) of Na+ and Cl− are not sufficiently high to attract or eject hydrogen ions to or from their hydration sheaths.
• CO32− + H+ → HCO3− • CO32− + 2H+ → H2CO30
Ion Hydrolysis
– Thus, when Al3+ ions are added to water, amounts of AlOH2+, Al(OH)2+, Al(OH)30 and Al(OH)4− ions are formed. Similarly, whenever CO32− ions are added to water, an equilibrium concentration of the hydrolysis products, HCO3− and H2CO30 form.
2-水化学成分和水化学指标
水化学成分和水化学指标
Ion Hydrolysis
– Dissolved substances that can donate a proton are called acids and those that can accept a proton are called bases. The key to understanding acid/base equilibria lies in the phenomenon of hydrolysis.
Ion Hydrolysis
– Cation hydrolysis thus results in a decrease in solution pH.
– Anion hydrolysis operates oppositely. Because of their negative charge, anions not only preserve the hydrogen ions of water molecules in their hydration sheaths but attract hydrogen ions from the bulk solution.
• Al3+ + H2O −→ AlOH2+ + H+ • Al3+ + 2H2O −→ Al(OH)2+ + 2H+ • Al3+ + 3H2O −→ Al(OH)30 + 3H+ • Al3+ + 4H2O −→ Al(OH)4− + 4H+
Ion Hydrolysis
– In the case of the pH increase associated with the addition of Na2CO3 to water, it is the CO32− ion that hydrolyzes. For CO32−, only two hydrolysis products form:
– Anion hydrolysis thus results in an increase in the solution pH.
Ion Hydrolysis
– Monovalent ions are so weakly charged that they rarely hydrolyze. For example, NaCl is considered a neutral salt, i.e., producing no effect on pH when it is added to water.
Ion Hydrolysis
– The addition of AlCl3 or Na2CO3 to water, however, causes a marked change in the pH of water. In the case of AlCl3, it is the Al3+ ion that hydrolyzes and several hydrolysis products form representing Al3+ ions that have lost one, two, three and four hydrogen ions from their hydration sheaths.
Ion Hydrolysis
Ion Hydrolysis
– Would the cation tend to repel and perhaps eject a hydrogen ion into the bulk solution?
– Certainly one would think so and the tendency would be greater the higher the charge on the caBaidu Nhomakorabeaions. The process of hydrogen ion detachment from hydration sheaths and their ejection into the bulk solution is called hydrolysis.
– Hydrolysis is a reaction that accompanies ion hydration. Hydrogen ions are labile and can transfer from one water molecule to the next in solution. Imagine the hydrogen ions associated with the first neighbor water molecules around a monovalent cation in solution.
– This is because the field strengths (charge/surface area ratios) of Na+ and Cl− are not sufficiently high to attract or eject hydrogen ions to or from their hydration sheaths.
• CO32− + H+ → HCO3− • CO32− + 2H+ → H2CO30
Ion Hydrolysis
– Thus, when Al3+ ions are added to water, amounts of AlOH2+, Al(OH)2+, Al(OH)30 and Al(OH)4− ions are formed. Similarly, whenever CO32− ions are added to water, an equilibrium concentration of the hydrolysis products, HCO3− and H2CO30 form.
2-水化学成分和水化学指标
水化学成分和水化学指标
Ion Hydrolysis
– Dissolved substances that can donate a proton are called acids and those that can accept a proton are called bases. The key to understanding acid/base equilibria lies in the phenomenon of hydrolysis.
Ion Hydrolysis
– Cation hydrolysis thus results in a decrease in solution pH.
– Anion hydrolysis operates oppositely. Because of their negative charge, anions not only preserve the hydrogen ions of water molecules in their hydration sheaths but attract hydrogen ions from the bulk solution.